| 1 | /* $Id: avl.c,v 1.2 2000-03-24 01:40:52 bird Exp $
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| 2 | *
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| 3 | * AVL-Tree (lookalike) implementation.
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| 4 | *
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| 5 | * Copyright (c) 1999 knut st. osmundsen
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| 6 | *
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| 7 | * Project Odin Software License can be found in LICENSE.TXT
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| 8 | *
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| 9 | */
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| 10 |
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| 11 | /*******************************************************************************
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| 12 | * Defined Constants And Macros *
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| 13 | *******************************************************************************/
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| 14 |
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| 15 | /*
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| 16 | * AVL helper macros.
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| 17 | */
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| 18 | #define AVL_HEIGHTOF(pNode) ((unsigned char)((pNode) != NULL ? pNode->uchHeight : 0))
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| 19 | #define max(a,b) (((a) > (b)) ? (a) : (b))
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| 20 |
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| 21 |
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| 22 | /*******************************************************************************
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| 23 | * Internal Functions *
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| 24 | *******************************************************************************/
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| 25 | #include <os2.h>
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| 26 | #include "avl.h"
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| 27 | #if defined(RING0) || defined(RING3)
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| 28 | #include "dev32.h"
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| 29 | #else
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| 30 | #define SSToDS(a) (a)
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| 31 | #endif
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| 32 | #include "string.h"
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| 33 |
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| 34 | #include <builtin.h>
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| 35 | #define assert(a) ((a) ? (void)0 : __interrupt(3))
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| 36 |
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| 37 |
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| 38 | /*******************************************************************************
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| 39 | * Structures and Typedefs *
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| 40 | *******************************************************************************/
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| 41 | /*
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| 42 | * A stack used to avoid recursive calls...
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| 43 | */
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| 44 | typedef struct _AVLStack
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| 45 | {
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| 46 | unsigned cEntries;
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| 47 | PPAVLNODECORE aEntries[AVL_MAX_HEIGHT];
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| 48 | } AVLSTACK, *PAVLSTACK;
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| 49 | typedef struct _AVLStack2
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| 50 | {
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| 51 | unsigned cEntries;
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| 52 | PAVLNODECORE aEntries[AVL_MAX_HEIGHT];
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| 53 | char achFlags[AVL_MAX_HEIGHT];
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| 54 | } AVLSTACK2, *PAVLSTACK2;
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| 55 |
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| 56 |
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| 57 | /*******************************************************************************
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| 58 | * Internal Functions *
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| 59 | *******************************************************************************/
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| 60 | _Inline void AVLRebalance(PAVLSTACK pStack);
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| 61 |
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| 62 |
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| 63 | /**
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| 64 | * Inserts a node into the AVL-tree.
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| 65 | * @returns TRUE if inserted.
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| 66 | * FALSE if node exists in tree.
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| 67 | * @param ppTree Pointer to the AVL-tree root node pointer.
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| 68 | * @param pNode Pointer to the node which is to be added.
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| 69 | * @sketch Find the location of the node (using binary three algorithm.):
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| 70 | * LOOP until NULL leaf pointer
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| 71 | * BEGIN
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| 72 | * Add node pointer pointer to the AVL-stack.
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| 73 | * IF new-node-key < node key THEN
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| 74 | * left
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| 75 | * ELSE
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| 76 | * right
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| 77 | * END
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| 78 | * Fill in leaf node and insert it.
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| 79 | * Rebalance the tree.
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| 80 | * @status completely implemented.
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| 81 | * @author knut st. osmundsen
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| 82 | */
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| 83 | BOOL AVLInsert(PPAVLNODECORE ppTree, PAVLNODECORE pNode)
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| 84 | {
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| 85 | AVLSTACK AVLStack;
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| 86 | PPAVLNODECORE ppCurNode = ppTree;
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| 87 | register AVLKEY Key = pNode->Key;
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| 88 | register PAVLNODECORE pCurNode;
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| 89 |
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| 90 | AVLStack.cEntries = 0;
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| 91 |
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| 92 | while ((pCurNode = *ppCurNode) != NULL)
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| 93 | {
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| 94 | assert(AVLStack.cEntries < AVL_MAX_HEIGHT);
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| 95 | assert(pNode != pCurNode);
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| 96 | AVLStack.aEntries[AVLStack.cEntries++] = ppCurNode;
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| 97 | #ifdef AVL_MAY_TRY_INSERT_EQUAL
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| 98 | /* check if equal */
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| 99 | if (AVL_E(pCurNode->Key, Key))
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| 100 | return FALSE;
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| 101 | #endif
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| 102 | if (AVL_G(pCurNode->Key, Key))
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| 103 | ppCurNode = &pCurNode->pLeft;
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| 104 | else
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| 105 | ppCurNode = &pCurNode->pRight;
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| 106 | }
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| 107 |
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| 108 | pNode->pLeft = pNode->pRight = NULL;
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| 109 | pNode->uchHeight = 1;
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| 110 | *ppCurNode = pNode;
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| 111 |
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| 112 | AVLRebalance(SSToDS(&AVLStack));
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| 113 | return TRUE;
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| 114 | }
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| 115 |
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| 116 |
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| 117 | /**
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| 118 | * Removes a node from the AVL-tree.
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| 119 | * @returns Pointer to the node.
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| 120 | * @param ppTree Pointer to the AVL-tree root node pointer.
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| 121 | * @param Key Key value of the node which is to be removed.
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| 122 | * @sketch Find the node which is to be removed:
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| 123 | * LOOP until not found
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| 124 | * BEGIN
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| 125 | * Add node pointer pointer to the AVL-stack.
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| 126 | * IF the keys matches THEN break!
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| 127 | * IF remove key < node key THEN
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| 128 | * left
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| 129 | * ELSE
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| 130 | * right
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| 131 | * END
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| 132 | * IF found THEN
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| 133 | * BEGIN
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| 134 | * IF left node not empty THEN
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| 135 | * BEGIN
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| 136 | * Find the right most node in the left tree while adding the pointer to the pointer to it's parent to the stack:
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| 137 | * Start at left node.
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| 138 | * LOOP until right node is empty
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| 139 | * BEGIN
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| 140 | * Add to stack.
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| 141 | * go right.
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| 142 | * END
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| 143 | * Link out the found node.
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| 144 | * Replace the node which is to be removed with the found node.
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| 145 | * Correct the stack entry for the pointer to the left tree.
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| 146 | * END
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| 147 | * ELSE
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| 148 | * BEGIN
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| 149 | * Move up right node.
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| 150 | * Remove last stack entry.
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| 151 | * END
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| 152 | * Balance tree using stack.
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| 153 | * END
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| 154 | * return pointer to the removed node (if found).
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| 155 | * @status completely implemented.
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| 156 | * @author knut st. osmundsen
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| 157 | */
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| 158 | PAVLNODECORE AVLRemove(PPAVLNODECORE ppTree, AVLKEY Key)
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| 159 | {
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| 160 | AVLSTACK AVLStack;
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| 161 | PPAVLNODECORE ppDeleteNode = ppTree;
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| 162 | register PAVLNODECORE pDeleteNode;
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| 163 |
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| 164 | AVLStack.cEntries = 0;
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| 165 |
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| 166 | while ((pDeleteNode = *ppDeleteNode) != NULL)
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| 167 | {
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| 168 | assert(AVLStack.cEntries < AVL_MAX_HEIGHT);
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| 169 | AVLStack.aEntries[AVLStack.cEntries++] = ppDeleteNode;
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| 170 | if (AVL_E(pDeleteNode->Key, Key))
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| 171 | break;
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| 172 |
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| 173 | if (AVL_G(pDeleteNode->Key, Key))
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| 174 | ppDeleteNode = &pDeleteNode->pLeft;
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| 175 | else
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| 176 | ppDeleteNode = &pDeleteNode->pRight;
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| 177 | }
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| 178 |
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| 179 | if (pDeleteNode != NULL)
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| 180 | {
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| 181 | if (pDeleteNode->pLeft != NULL)
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| 182 | {
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| 183 | unsigned iStackEntry = AVLStack.cEntries;
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| 184 | PPAVLNODECORE ppLeftLeast = &pDeleteNode->pLeft;
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| 185 | register PAVLNODECORE pLeftLeast;
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| 186 |
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| 187 | while ((pLeftLeast = *ppLeftLeast)->pRight != NULL) /* Left most node. */
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| 188 | {
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| 189 | assert(AVLStack.cEntries < AVL_MAX_HEIGHT);
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| 190 | AVLStack.aEntries[AVLStack.cEntries++] = ppLeftLeast;
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| 191 | ppLeftLeast = &pLeftLeast->pRight;
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| 192 | pLeftLeast = pLeftLeast->pRight;
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| 193 | }
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| 194 |
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| 195 | /* link out pLeftLeast */
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| 196 | *ppLeftLeast = pLeftLeast->pLeft;
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| 197 |
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| 198 | /* link in place of the delete node. */
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| 199 | pLeftLeast->pLeft = pDeleteNode->pLeft;
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| 200 | pLeftLeast->pRight = pDeleteNode->pRight;
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| 201 | pLeftLeast->uchHeight = pDeleteNode->uchHeight;
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| 202 | *ppDeleteNode = pLeftLeast;
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| 203 | AVLStack.aEntries[iStackEntry] = &pLeftLeast->pLeft;
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| 204 | }
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| 205 | else
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| 206 | {
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| 207 | *ppDeleteNode = pDeleteNode->pRight;
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| 208 | AVLStack.cEntries--;
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| 209 | }
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| 210 |
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| 211 | AVLRebalance(SSToDS(&AVLStack));
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| 212 | }
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| 213 |
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| 214 | return pDeleteNode;
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| 215 | }
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| 216 |
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| 217 |
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| 218 | /**
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| 219 | * Gets a node from the tree (does not remove it!)
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| 220 | * @returns Pointer to the node holding the given key.
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| 221 | * @param ppTree Pointer to the AVL-tree root node pointer.
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| 222 | * @param Key Key value of the node which is to be found.
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| 223 | * @sketch
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| 224 | * @status completely implemented.
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| 225 | * @author knut st. osmundsen
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| 226 | */
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| 227 | PAVLNODECORE AVLGet(PPAVLNODECORE ppTree, AVLKEY Key)
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| 228 | {
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| 229 | register PAVLNODECORE pNode = *ppTree;
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| 230 |
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| 231 | while (pNode != NULL && AVL_NE(pNode->Key, Key))
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| 232 | {
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| 233 | if (AVL_G(pNode->Key, Key))
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| 234 | pNode = pNode->pLeft;
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| 235 | else
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| 236 | pNode = pNode->pRight;
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| 237 | }
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| 238 |
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| 239 | return pNode;
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| 240 | }
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| 241 |
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| 242 |
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| 243 |
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| 244 | /**
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| 245 | * Gets a node from the tree and its parent node (if any) (does not remove any nodes!)
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| 246 | * @returns Pointer to the node holding the given key.
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| 247 | * @param ppTree Pointer to the AVL-tree root node pointer.
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| 248 | * @param ppParent Pointer to a variable which will hold the pointer to the partent node on
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| 249 | * return. When no node is found, this will hold the last searched node.
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| 250 | * @param Key Key value of the node which is to be found.
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| 251 | * @sketch
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| 252 | * @status completely implemented.
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| 253 | * @author knut st. osmundsen
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| 254 | */
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| 255 | PAVLNODECORE AVLGetWithParent(PPAVLNODECORE ppTree, PPAVLNODECORE ppParent, AVLKEY Key)
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| 256 | {
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| 257 | register PAVLNODECORE pNode = *ppTree;
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| 258 | register PAVLNODECORE pParent = NULL;
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| 259 |
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| 260 | while (pNode != NULL && AVL_NE(pNode->Key, Key))
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| 261 | {
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| 262 | pParent = pNode;
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| 263 | if (AVL_G(pNode->Key, Key))
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| 264 | pNode = pNode->pLeft;
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| 265 | else
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| 266 | pNode = pNode->pRight;
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| 267 | }
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| 268 |
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| 269 | *ppParent = pParent;
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| 270 | return pNode;
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| 271 | }
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| 272 |
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| 273 |
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| 274 |
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| 275 | /**
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| 276 | * Gets node from the tree (does not remove it!) and it's adjecent (by key value) nodes.
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| 277 | * @returns Pointer to the node holding the given key.
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| 278 | * @param ppTree Pointer to the AVL-tree root node pointer.
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| 279 | * @param Key Key value of the node which is to be found.
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| 280 | * @param ppLeft Pointer to left node pointer.
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| 281 | * @param ppRight Pointer to right node pointer.
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| 282 | * @sketch Find node with the given key, record search path on the stack.
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| 283 | * IF found THEN
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| 284 | * BEGIN
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| 285 | * Find the right-most node in the left subtree.
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| 286 | * Find the left-most node in the right subtree.
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| 287 | * Rewind the stack while searching for more adjecent nodes.
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| 288 | * END
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| 289 | * return node with adjecent nodes.
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| 290 | * @status completely implemented.
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| 291 | * @author knut st. osmundsen
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| 292 | */
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| 293 | PAVLNODECORE AVLGetWithAdjecentNodes(PPAVLNODECORE ppTree, AVLKEY Key, PPAVLNODECORE ppLeft, PPAVLNODECORE ppRight)
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| 294 | {
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| 295 | AVLSTACK AVLStack;
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| 296 | PPAVLNODECORE ppNode = ppTree;
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| 297 | PAVLNODECORE pNode;
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| 298 |
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| 299 | AVLStack.cEntries = 0;
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| 300 |
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| 301 | while ((pNode = *ppNode) != NULL && AVL_NE(pNode->Key, Key))
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| 302 | {
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| 303 | assert(AVLStack.cEntries < AVL_MAX_HEIGHT);
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| 304 | AVLStack.aEntries[AVLStack.cEntries++] = ppNode;
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| 305 | if (AVL_G(pNode->Key, Key))
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| 306 | ppNode = &pNode->pLeft;
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| 307 | else
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| 308 | ppNode = &pNode->pRight;
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| 309 | }
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| 310 |
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| 311 | if (pNode != NULL)
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| 312 | {
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| 313 | PAVLNODECORE pCurNode;
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| 314 |
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| 315 | /* find rigth-most node in left subtree. */
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| 316 | pCurNode = pNode->pLeft;
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| 317 | if (pCurNode != NULL)
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| 318 | while (pCurNode->pRight != NULL)
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| 319 | pCurNode = pCurNode->pRight;
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| 320 | *ppLeft = pCurNode;
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| 321 |
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| 322 | /* find left-most node in right subtree. */
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| 323 | pCurNode = pNode->pRight;
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| 324 | if (pCurNode != NULL)
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| 325 | while (pCurNode->pLeft != NULL)
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| 326 | pCurNode = pCurNode->pLeft;
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| 327 | *ppRight = pCurNode;
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| 328 |
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| 329 | /* rewind stack */
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| 330 | while (AVLStack.cEntries-- > 0)
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| 331 | {
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| 332 | pCurNode = *AVLStack.aEntries[AVLStack.cEntries];
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| 333 | if (AVL_L(pCurNode->Key, Key) && (*ppLeft == NULL || AVL_G(pCurNode->Key, (*ppLeft)->Key)))
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| 334 | *ppLeft = pCurNode;
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| 335 | else if (AVL_G(pCurNode->Key, Key) && (*ppRight == NULL || AVL_L(pCurNode->Key, (*ppRight)->Key)))
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| 336 | *ppRight = pCurNode;
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| 337 | }
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| 338 | }
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| 339 | else
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| 340 | *ppLeft = *ppRight = NULL;
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| 341 |
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| 342 | return pNode;
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| 343 | }
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| 344 |
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| 345 |
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| 346 | /**
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| 347 | * Iterates tru all nodes in the given tree.
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| 348 | * @returns 0 on success. Return from callback on failiure.
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| 349 | * @param ppTree Pointer to the AVL-tree root node pointer.
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| 350 | * @param fFromLeft TRUE: Left to right.
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| 351 | * FALSE: Right to left.
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| 352 | * @param pfnCallBack Pointer to callback function.
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| 353 | * @param pvParam Userparameter passed on to the callback function.
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| 354 | * @status completely implemented.
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| 355 | * @author knut st. osmundsen
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| 356 | */
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| 357 | unsigned AVLDoWithAll(PPAVLNODECORE ppTree, int fFromLeft, PAVLCALLBACK pfnCallBack, void *pvParam)
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| 358 | {
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| 359 | AVLSTACK2 AVLStack;
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| 360 | PAVLNODECORE pNode;
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| 361 | unsigned rc;
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| 362 |
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| 363 | if (*ppTree == NULL)
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| 364 | return 0;
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| 365 |
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| 366 | AVLStack.cEntries = 1;
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| 367 | AVLStack.achFlags[0] = 0;
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| 368 | AVLStack.aEntries[0] = *ppTree;
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| 369 |
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| 370 | if (fFromLeft)
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| 371 | { /* from left */
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| 372 | while (AVLStack.cEntries > 0)
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| 373 | {
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| 374 | pNode = AVLStack.aEntries[AVLStack.cEntries - 1];
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| 375 |
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| 376 | /* left */
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| 377 | if (!AVLStack.achFlags[AVLStack.cEntries - 1]++)
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| 378 | {
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| 379 | if (pNode->pLeft != NULL)
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| 380 | {
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| 381 | AVLStack.achFlags[AVLStack.cEntries] = 0; /* 0 first, 1 last */
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| 382 | AVLStack.aEntries[AVLStack.cEntries++] = pNode->pLeft;
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| 383 | continue;
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| 384 | }
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| 385 | }
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| 386 |
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| 387 | /* center */
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| 388 | rc = pfnCallBack(pNode, pvParam);
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| 389 | if (rc != 0)
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| 390 | return rc;
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| 391 |
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| 392 | /* right */
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| 393 | AVLStack.cEntries--;
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| 394 | if (pNode->pRight != NULL)
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| 395 | {
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| 396 | AVLStack.achFlags[AVLStack.cEntries] = 0;
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| 397 | AVLStack.aEntries[AVLStack.cEntries++] = pNode->pRight;
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| 398 | }
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| 399 | } /* while */
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| 400 | }
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| 401 | else
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| 402 | { /* from right */
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| 403 | while (AVLStack.cEntries > 0)
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| 404 | {
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| 405 | pNode = AVLStack.aEntries[AVLStack.cEntries - 1];
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| 406 |
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| 407 |
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| 408 | /* right */
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| 409 | if (!AVLStack.achFlags[AVLStack.cEntries - 1]++)
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| 410 | {
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| 411 | if (pNode->pRight != NULL)
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| 412 | {
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| 413 | AVLStack.achFlags[AVLStack.cEntries] = 0; /* 0 first, 1 last */
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| 414 | AVLStack.aEntries[AVLStack.cEntries++] = pNode->pRight;
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| 415 | continue;
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| 416 | }
|
|---|
| 417 | }
|
|---|
| 418 |
|
|---|
| 419 | /* center */
|
|---|
| 420 | rc = pfnCallBack(pNode, pvParam);
|
|---|
| 421 | if (rc != 0)
|
|---|
| 422 | return rc;
|
|---|
| 423 |
|
|---|
| 424 | /* left */
|
|---|
| 425 | AVLStack.cEntries--;
|
|---|
| 426 | if (pNode->pLeft != NULL)
|
|---|
| 427 | {
|
|---|
| 428 | AVLStack.achFlags[AVLStack.cEntries] = 0;
|
|---|
| 429 | AVLStack.aEntries[AVLStack.cEntries++] = pNode->pLeft;
|
|---|
| 430 | }
|
|---|
| 431 | } /* while */
|
|---|
| 432 | }
|
|---|
| 433 |
|
|---|
| 434 | return 0;
|
|---|
| 435 | }
|
|---|
| 436 |
|
|---|
| 437 |
|
|---|
| 438 | /**
|
|---|
| 439 | * Starts an enumeration of all nodes in the given AVL tree.
|
|---|
| 440 | * @returns Pointer to the first node in the tree.
|
|---|
| 441 | * @param ppTree Pointer to the AVL-tree root node pointer.
|
|---|
| 442 | * @param pEnumData Pointer to enumeration control data.
|
|---|
| 443 | * @param fFromLeft TRUE: Left to right.
|
|---|
| 444 | * FALSE: Right to left.
|
|---|
| 445 | * @status completely implemented.
|
|---|
| 446 | * @author knut st. osmundsen
|
|---|
| 447 | */
|
|---|
| 448 | PAVLNODECORE AVLBeginEnumTree(PPAVLNODECORE ppTree, PAVLENUMDATA pEnumData, int fFromLeft)
|
|---|
| 449 | {
|
|---|
| 450 | if (*ppTree != NULL)
|
|---|
| 451 | {
|
|---|
| 452 | pEnumData->fFromLeft = (char)fFromLeft;
|
|---|
| 453 | pEnumData->cEntries = 1;
|
|---|
| 454 | pEnumData->aEntries[0] = *ppTree;
|
|---|
| 455 | pEnumData->achFlags[0] = 0;
|
|---|
| 456 | }
|
|---|
| 457 | else
|
|---|
| 458 | pEnumData->cEntries = 0;
|
|---|
| 459 |
|
|---|
| 460 | return AVLGetNextNode(pEnumData);
|
|---|
| 461 | }
|
|---|
| 462 |
|
|---|
| 463 |
|
|---|
| 464 | /**
|
|---|
| 465 | * Get the next node in the tree enumeration.
|
|---|
| 466 | * @returns Pointer to the first node in the tree.
|
|---|
| 467 | * @param pEnumData Pointer to enumeration control data.
|
|---|
| 468 | * @status completely implemented.
|
|---|
| 469 | * @author knut st. osmundsen
|
|---|
| 470 | */
|
|---|
| 471 | PAVLNODECORE AVLGetNextNode(PAVLENUMDATA pEnumData)
|
|---|
| 472 | {
|
|---|
| 473 | PAVLNODECORE pNode;
|
|---|
| 474 |
|
|---|
| 475 | if (pEnumData->fFromLeft)
|
|---|
| 476 | { /* from left */
|
|---|
| 477 | while (pEnumData->cEntries > 0)
|
|---|
| 478 | {
|
|---|
| 479 | pNode = pEnumData->aEntries[pEnumData->cEntries - 1];
|
|---|
| 480 |
|
|---|
| 481 | /* left */
|
|---|
| 482 | if (pEnumData->achFlags[pEnumData->cEntries - 1] == 0)
|
|---|
| 483 | {
|
|---|
| 484 | pEnumData->achFlags[pEnumData->cEntries - 1]++;
|
|---|
| 485 | if (pNode->pLeft != NULL)
|
|---|
| 486 | {
|
|---|
| 487 | pEnumData->achFlags[pEnumData->cEntries] = 0; /* 0 left, 1 center, 2 right */
|
|---|
| 488 | pEnumData->aEntries[pEnumData->cEntries++] = pNode->pLeft;
|
|---|
| 489 | continue;
|
|---|
| 490 | }
|
|---|
| 491 | }
|
|---|
| 492 |
|
|---|
| 493 | /* center */
|
|---|
| 494 | if (pEnumData->achFlags[pEnumData->cEntries - 1] == 1)
|
|---|
| 495 | {
|
|---|
| 496 | pEnumData->achFlags[pEnumData->cEntries - 1]++;
|
|---|
| 497 | return pNode;
|
|---|
| 498 | }
|
|---|
| 499 |
|
|---|
| 500 | /* right */
|
|---|
| 501 | pEnumData->cEntries--;
|
|---|
| 502 | if (pNode->pRight != NULL)
|
|---|
| 503 | {
|
|---|
| 504 | pEnumData->achFlags[pEnumData->cEntries] = 0;
|
|---|
| 505 | pEnumData->aEntries[pEnumData->cEntries++] = pNode->pRight;
|
|---|
| 506 | }
|
|---|
| 507 | } /* while */
|
|---|
| 508 | }
|
|---|
| 509 | else
|
|---|
| 510 | { /* from right */
|
|---|
| 511 | while (pEnumData->cEntries > 0)
|
|---|
| 512 | {
|
|---|
| 513 | pNode = pEnumData->aEntries[pEnumData->cEntries - 1];
|
|---|
| 514 |
|
|---|
| 515 |
|
|---|
| 516 | /* right */
|
|---|
| 517 | if (pEnumData->achFlags[pEnumData->cEntries - 1] == 0)
|
|---|
| 518 | {
|
|---|
| 519 | pEnumData->achFlags[pEnumData->cEntries - 1]++;
|
|---|
| 520 | if (pNode->pRight != NULL)
|
|---|
| 521 | {
|
|---|
| 522 | pEnumData->achFlags[pEnumData->cEntries] = 0; /* 0 right, 1 center, 2 left */
|
|---|
| 523 | pEnumData->aEntries[pEnumData->cEntries++] = pNode->pRight;
|
|---|
| 524 | continue;
|
|---|
| 525 | }
|
|---|
| 526 | }
|
|---|
| 527 |
|
|---|
| 528 | /* center */
|
|---|
| 529 | if (pEnumData->achFlags[pEnumData->cEntries - 1] == 1)
|
|---|
| 530 | {
|
|---|
| 531 | pEnumData->achFlags[pEnumData->cEntries - 1]++;
|
|---|
| 532 | return pNode;
|
|---|
| 533 | }
|
|---|
| 534 |
|
|---|
| 535 | /* left */
|
|---|
| 536 | pEnumData->cEntries--;
|
|---|
| 537 | if (pNode->pLeft != NULL)
|
|---|
| 538 | {
|
|---|
| 539 | pEnumData->achFlags[pEnumData->cEntries] = 0;
|
|---|
| 540 | pEnumData->aEntries[pEnumData->cEntries++] = pNode->pLeft;
|
|---|
| 541 | }
|
|---|
| 542 | } /* while */
|
|---|
| 543 | }
|
|---|
| 544 |
|
|---|
| 545 | return NULL;
|
|---|
| 546 |
|
|---|
| 547 | }
|
|---|
| 548 |
|
|---|
| 549 |
|
|---|
| 550 |
|
|---|
| 551 |
|
|---|
| 552 | /**
|
|---|
| 553 | * Finds the best fitting node in the tree for the given Key value.
|
|---|
| 554 | * @returns Pointer to the best fitting node found.
|
|---|
| 555 | * @param ppTree Pointer to Pointer to the tree root node.
|
|---|
| 556 | * @param Key The Key of which is to be found a best fitting match for..
|
|---|
| 557 | * @param fAbove TRUE: Returned node is have the closest key to Key from above.
|
|---|
| 558 | * FALSE: Returned node is have the closest key to Key from below.
|
|---|
| 559 | * @status completely implemented.
|
|---|
| 560 | * @sketch The best fitting node is always located in the searchpath above you.
|
|---|
| 561 | * >= (above): The node where you last turned left.
|
|---|
| 562 | * <= (below): the node where you last turned right.
|
|---|
| 563 | * @author knut st. osmundsen
|
|---|
| 564 | */
|
|---|
| 565 | PAVLNODECORE AVLGetBestFit(PPAVLNODECORE ppTree, AVLKEY Key, int fAbove)
|
|---|
| 566 | {
|
|---|
| 567 | register PAVLNODECORE pNode = *ppTree;
|
|---|
| 568 | PAVLNODECORE pNodeLast = NULL;
|
|---|
| 569 |
|
|---|
| 570 | if (fAbove)
|
|---|
| 571 | { /* pNode->Key >= Key */
|
|---|
| 572 | while (pNode != NULL && AVL_NE(pNode->Key, Key))
|
|---|
| 573 | {
|
|---|
| 574 | if (AVL_G(pNode->Key, Key))
|
|---|
| 575 | {
|
|---|
| 576 | pNodeLast = pNode;
|
|---|
| 577 | pNode = pNode->pLeft;
|
|---|
| 578 | }
|
|---|
| 579 | else
|
|---|
| 580 | pNode = pNode->pRight;
|
|---|
| 581 | }
|
|---|
| 582 | }
|
|---|
| 583 | else
|
|---|
| 584 | { /* pNode->Key <= Key */
|
|---|
| 585 | while (pNode != NULL && AVL_NE(pNode->Key, Key))
|
|---|
| 586 | {
|
|---|
| 587 | if (AVL_L(pNode->Key, Key))
|
|---|
| 588 | {
|
|---|
| 589 | pNodeLast = pNode;
|
|---|
| 590 | pNode = pNode->pRight;
|
|---|
| 591 | }
|
|---|
| 592 | else
|
|---|
| 593 | pNode = pNode->pLeft;
|
|---|
| 594 | }
|
|---|
| 595 | }
|
|---|
| 596 |
|
|---|
| 597 | return pNode == NULL ? pNodeLast /* best fit */ : pNode /* perfect match */;
|
|---|
| 598 | }
|
|---|
| 599 |
|
|---|
| 600 |
|
|---|
| 601 | /**
|
|---|
| 602 | * Rewindes a stack of pointer to pointers to nodes, rebalancing the tree.
|
|---|
| 603 | * @param pStack Pointer to stack to rewind.
|
|---|
| 604 | * @sketch LOOP thru all stack entries
|
|---|
| 605 | * BEGIN
|
|---|
| 606 | * Get pointer to pointer to node (and pointer to node) from stack.
|
|---|
| 607 | * IF 2 higher left subtree than in right subtree THEN
|
|---|
| 608 | * BEGIN
|
|---|
| 609 | * IF higher (or equal) left-sub-subtree than right-sub-subtree THEN
|
|---|
| 610 | * * n+2|n+3
|
|---|
| 611 | * / \ / \
|
|---|
| 612 | * n+2 n ==> n+1 n+1|n+2
|
|---|
| 613 | * / \ / \
|
|---|
| 614 | * n+1 n|n+1 n|n+1 n
|
|---|
| 615 | *
|
|---|
| 616 | * Or with keys:
|
|---|
| 617 | *
|
|---|
| 618 | * 4 2
|
|---|
| 619 | * / \ / \
|
|---|
| 620 | * 2 5 ==> 1 4
|
|---|
| 621 | * / \ / \
|
|---|
| 622 | * 1 3 3 5
|
|---|
| 623 | *
|
|---|
| 624 | * ELSE
|
|---|
| 625 | * * n+2
|
|---|
| 626 | * / \ / \
|
|---|
| 627 | * n+2 n n+1 n+1
|
|---|
| 628 | * / \ ==> / \ / \
|
|---|
| 629 | * n n+1 n L R n
|
|---|
| 630 | * / \
|
|---|
| 631 | * L R
|
|---|
| 632 | *
|
|---|
| 633 | * Or with keys:
|
|---|
| 634 | * 6 4
|
|---|
| 635 | * / \ / \
|
|---|
| 636 | * 2 7 ==> 2 6
|
|---|
| 637 | * / \ / \ / \
|
|---|
| 638 | * 1 4 1 3 5 7
|
|---|
| 639 | * / \
|
|---|
| 640 | * 3 5
|
|---|
| 641 | * END
|
|---|
| 642 | * ELSE IF 2 higher in right subtree than in left subtree THEN
|
|---|
| 643 | * BEGIN
|
|---|
| 644 | * Same as above but left <==> right. (invert the picture)
|
|---|
| 645 | * ELSE
|
|---|
| 646 | * IF correct height THEN break
|
|---|
| 647 | * ELSE correct height.
|
|---|
| 648 | * END
|
|---|
| 649 | * @status
|
|---|
| 650 | * @author knut st. osmundsen
|
|---|
| 651 | * @remark
|
|---|
| 652 | */
|
|---|
| 653 | _Inline void AVLRebalance(PAVLSTACK pStack)
|
|---|
| 654 | {
|
|---|
| 655 | while (pStack->cEntries > 0)
|
|---|
| 656 | {
|
|---|
| 657 | PPAVLNODECORE ppNode = pStack->aEntries[--pStack->cEntries];
|
|---|
| 658 | PAVLNODECORE pNode = *ppNode;
|
|---|
| 659 | PAVLNODECORE pLeftNode = pNode->pLeft;
|
|---|
| 660 | unsigned char uchLeftHeight = AVL_HEIGHTOF(pLeftNode);
|
|---|
| 661 | PAVLNODECORE pRightNode = pNode->pRight;
|
|---|
| 662 | unsigned char uchRightHeight = AVL_HEIGHTOF(pRightNode);
|
|---|
| 663 |
|
|---|
| 664 | if (uchRightHeight + 1 < uchLeftHeight)
|
|---|
| 665 | {
|
|---|
| 666 | PAVLNODECORE pLeftLeftNode = pLeftNode->pLeft;
|
|---|
| 667 | PAVLNODECORE pLeftRightNode = pLeftNode->pRight;
|
|---|
| 668 | unsigned char uchLeftRightHeight = AVL_HEIGHTOF(pLeftRightNode);
|
|---|
| 669 |
|
|---|
| 670 | if (AVL_HEIGHTOF(pLeftLeftNode) >= uchLeftRightHeight)
|
|---|
| 671 | {
|
|---|
| 672 | pNode->pLeft = pLeftRightNode;
|
|---|
| 673 | pLeftNode->pRight = pNode;
|
|---|
| 674 | pLeftNode->uchHeight = (unsigned char)(1 + (pNode->uchHeight = (unsigned char)(1 + uchLeftRightHeight)));
|
|---|
| 675 | *ppNode = pLeftNode;
|
|---|
| 676 | }
|
|---|
| 677 | else
|
|---|
| 678 | {
|
|---|
| 679 | pLeftNode->pRight = pLeftRightNode->pLeft;
|
|---|
| 680 | pNode->pLeft = pLeftRightNode->pRight;
|
|---|
| 681 | pLeftRightNode->pLeft = pLeftNode;
|
|---|
| 682 | pLeftRightNode->pRight = pNode;
|
|---|
| 683 | pLeftNode->uchHeight = pNode->uchHeight = uchLeftRightHeight;
|
|---|
| 684 | pLeftRightNode->uchHeight = uchLeftHeight;
|
|---|
| 685 | *ppNode = pLeftRightNode;
|
|---|
| 686 | }
|
|---|
| 687 | }
|
|---|
| 688 | else if (uchLeftHeight + 1 < uchRightHeight)
|
|---|
| 689 | {
|
|---|
| 690 | PAVLNODECORE pRightLeftNode = pRightNode->pLeft;
|
|---|
| 691 | unsigned char uchRightLeftHeight = AVL_HEIGHTOF(pRightLeftNode);
|
|---|
| 692 | PAVLNODECORE pRightRightNode = pRightNode->pRight;
|
|---|
| 693 |
|
|---|
| 694 | if (AVL_HEIGHTOF(pRightRightNode) >= uchRightLeftHeight)
|
|---|
| 695 | {
|
|---|
| 696 | pNode->pRight = pRightLeftNode;
|
|---|
| 697 | pRightNode->pLeft = pNode;
|
|---|
| 698 | pRightNode->uchHeight = (unsigned char)(1 + (pNode->uchHeight = (unsigned char)(1 + uchRightLeftHeight)));
|
|---|
| 699 | *ppNode = pRightNode;
|
|---|
| 700 | }
|
|---|
| 701 | else
|
|---|
| 702 | {
|
|---|
| 703 | pRightNode->pLeft = pRightLeftNode->pRight;
|
|---|
| 704 | pNode->pRight = pRightLeftNode->pLeft;
|
|---|
| 705 | pRightLeftNode->pRight = pRightNode;
|
|---|
| 706 | pRightLeftNode->pLeft = pNode;
|
|---|
| 707 | pRightNode->uchHeight = pNode->uchHeight = uchRightLeftHeight;
|
|---|
| 708 | pRightLeftNode->uchHeight = uchRightHeight;
|
|---|
| 709 | *ppNode = pRightLeftNode;
|
|---|
| 710 | }
|
|---|
| 711 | }
|
|---|
| 712 | else
|
|---|
| 713 | {
|
|---|
| 714 | register unsigned char uchHeight = (unsigned char)(max(uchLeftHeight, uchRightHeight) + 1);
|
|---|
| 715 | if (uchHeight == pNode->uchHeight)
|
|---|
| 716 | break;
|
|---|
| 717 | pNode->uchHeight = uchHeight;
|
|---|
| 718 | }
|
|---|
| 719 | }
|
|---|
| 720 | }
|
|---|
| 721 |
|
|---|