用c做存储之二:avl树结构、应用场景及实现

2/10/2017来源:ASP.NET技巧人气:240

avl树用于存储大量非相关数据,并且在动态更新时能够快速平衡。 avl树实现实例:

typedef struct { UINT8 Name[MAX_DIAGLOG_TYPE_NAME_LEN]; /*业务注册类型名*/ }DIAGLOG_REG; /* 诊断日志注册数据结构,使用时先memset清0 */ typedef struct { AVL_NODE Node; /*平衡树结点*/ DIAGLOG_REG DiaglogReg; }DIAGLOG_REG_NODE; DIAGLOG_REG_NODE * p_DiagLogRegNode = NULL; //结点名称属性比较函数 INT32S Diaglog_RegAvlNodeCmp(void * v_Node, GENERIC_ARGUMENT v_Key) { DIAGLOG_REG_NODE* PRegNode = (DIAGLOG_REG_NODE *)v_Node; return strncmp(v_Key.p, (char *)pRegNode->DiaglogReg.Name, MAX_DIAGLOG_TYPE_NAME_LEN); } DIAGLOG_REG_NODE *Diaglog_RegAvlNodeGet(UINT8* key) { DIAGLOG_REG_NODE* pRegNode = NULL; GENERIC_ARGUMENT GenericArg = {0}; GenericArg.p = (void *)key; pRegNode = (DIAGLOG_REG_NODE*)avlSearch((AVL_TREE)(p_DiagLogRegNode), GenericArg, Diaglog_RegAvlNodeCmp); return pRegNode; } INT32S Diaglog_RegAddAvlNode(DIAGLOG_REG_NODE * v_Node) { GENERIC_ARGUMENT GenericArg = {0}; DIAGLOG_REG_NODE* pRegNode = NULL; pRegNode = Diaglog_RegAvlNodeGet(v_Node->DiaglogReg.Name); if (NULL != pRegNode) { return ERROR; } pRegNode = Diaglog_UniAlloc(sizeof(DIAGLOG_REG_NODE)); if (NULL == pRegNode) { return ERROR; } memset(pRegNode, 0, sizeof(DIAGLOG_REG_NODE)); memmove(&pRegNode->DiaglogReg, &v_Node->DiaglogReg, sizeof(DIAGLOG_REG)); GenericArg.p = (void*)v_Node->DiaglogReg.Name; if (OK == avlInsert((AVL_TREE *)&p_DiagLogRegNode, pRegNode, GenericArg, Diaglog_RegAvlNodeCmp)) { return OK; } else { return ERROR; } } DIAGLOG_REG_NODE * Diaglog_RegAvlNodeGetFirst(void) { DIAGLOG_REG_NODE * pRegNode = NULL; pRegNode = (DIAGLOG_REG_NODE *)avlMinimumGet((AVL_TREE)p_DiagLogRegNode); return pRegNode; } DIAGLOG_REG_NODE *Diaglog_RegAvlNodeGetNext(UINT8* key) { GENERIC_ARGUMENT genericArg = {0}; if (0==strlen((char *)key)) { return Diaglog_RegAvlNodeGetFirst(); } genericArg.p = (void *)key; return (DIAGLOG_REG_NODE *)avlSuccessorGet((AVL_TREE)p_DiagLogRegNode, genericArg, Diaglog_RegAvlNodeCmp); } void Diaglog_RegDelAvlNode(UINT8* key) { DIAGLOG_REG_NODE * pRegNode = NULL; GENERIC_ARGUMENT genericArg = {0}; genericArg.p = (void*)key; pRegNode = (DIAGLOG_REG_NODE *)avlDelete((AVL_TREE *)&p_DiagLogRegNode, genericArg, Diaglog_RegAvlNodeCmp); if (NULL == pRegNode) { return; } Diaglog_FreeBuf((void *)pRegNode); }

avl树库函数源码 头文件

/* avlLib.h - AVL trees library header file */ /* Copyright 1999 Wind River Systems, Inc. */ /* modification history -------------------- 01f,24jan01,sn end file with newline(!) to avoid cpp errors 01e,10feb00,abd added avlMinimumGet and avlMaximumGet 01d,10feb00,abd added avlTreeWalk, avlTreePrint, avlTreeErase, avlTreePrintErase 01c,03feb00,abd added avlInsertInform, avlRemoveInsert 01b,24jan00,abd added avlSuccessorGet and avlPredecessorGet 01a,08feb99,wkn created. */ #ifndef __INCavlLibh #define __INCavlLibh #ifdef __cplusplus extern "C" { #endif /* typedefs */ /*#ifndef _My_AvlLib_H*/ typedef struct { void * left; /* pointer to the left subtree */ void * right; /* pointer to the right subtree */ int height; /* height of the subtree rooted at this node */ } AVL_NODE; typedef AVL_NODE * AVL_TREE; /* points to the root node of the tree */ typedef union { int i; UINT u; void * p; } GENERIC_ARGUMENT; /*#endif*/ /* function declarations */ void avlRebalance (AVL_NODE *** ancestors, int count); void * avlSearch (AVL_TREE root, GENERIC_ARGUMENT key, int compare (void *, GENERIC_ARGUMENT)); void * avlSuccessorGet (AVL_TREE root, GENERIC_ARGUMENT key, int compare (void *, GENERIC_ARGUMENT)); void * avlPredecessorGet (AVL_TREE root, GENERIC_ARGUMENT key, int compare (void *, GENERIC_ARGUMENT)); void * avlMinimumGet (AVL_TREE root); void * avlMaximumGet (AVL_TREE root); STATUS avlInsert (AVL_TREE * root, void * newNode, GENERIC_ARGUMENT key, int compare (void *, GENERIC_ARGUMENT)); STATUS avlInsertInform (AVL_TREE * pRoot, void * pNewNode, GENERIC_ARGUMENT key, void ** ppKeyHolder, int compare (void *, GENERIC_ARGUMENT)); void * avlRemoveInsert (AVL_TREE * pRoot, void * pNewNode, GENERIC_ARGUMENT key, int compare (void *, GENERIC_ARGUMENT)); void * avlDelete (AVL_TREE * root, GENERIC_ARGUMENT key, int compare (void *, GENERIC_ARGUMENT)); STATUS avlTreeWalk(AVL_TREE * pRoot, void walkExec(AVL_TREE * nodepp)); STATUS avlTreeWalkWithPara(AVL_TREE * pRoot, void walkExec(AVL_TREE * ppNode, void * v_Para), void * v_Para); STATUS avlTreePrint(AVL_TREE * pRoot, void printNode(void * nodep)); STATUS avlTreeErase(AVL_TREE * pRoot); STATUS avlTreePrintErase(AVL_TREE * pRoot, void printNode(void * nodep)); /* specialized implementation functions */ void * avlSearchUnsigned (AVL_TREE root, UINT key); STATUS avlInsertUnsigned (AVL_TREE * root, void * newNode); void * avlDeleteUnsigned (AVL_TREE * root, UINT key); #ifndef AVLTREE_FREE_FUNC_DEFINED #define AVLTREE_FREE_FUNC_DEFINED typedef void (*AVLTREE_FREE_FUNC)(void *); #endif STATUS avlTreeEraseWithFunc(AVL_TREE * pRoot, AVLTREE_FREE_FUNC v_Func); #ifdef __cplusplus } #endif #endif /* __INCavlLibh */

c文件

/* avlLib.c - AVL trees library */ /* Copyright 1999 Wind River Systems, Inc. */ #include "copyright_wrs.h" /* modification history -------------------- 01e,10feb00,abd added avlMinimumGet and avlMaximumGet 01d,10feb00,abd added avlTreeWalk, avlTreePrint, avlTreeErase, avlTreePrintErase 01c,03feb00,abd added avlInsertInform, avlRemoveInsert 01b,24jan00,abd added avlSuccessorGet and avlPredecessorGet 01a,08feb99,wkn created. */ /* DESCRipTION This library provides routines to manage some partially-balanced binary trees using the AVL algorithm. The tree nodes are ordered according to a given fully ordered relation, and there cannot be two nodes in the tree that are considered as equals by this relation. A balancing algorithm is run after each insertion or deletion Operation. The balancing algorithm is guaranteed to run in time proportional to the height of the tree, and this height is guaranteed to only grow with log(N) where N is the number of nodes in the tree. Thus searching, insertion and deletion are all guaranteed to run in time proportional to log(N). Because the rebalancing operation might require re-rooting the binary tree, the arguments to the insertion and deletion operations cannot be simply pointers to the root node but they need to be pointers to the root node pointer. This way the root node pointer can be modified when the binary tree is re-rooted. In order to save some memory, the tree nodes does not contains pointers to their parent node. However, the rebalancing operation needs to walk from a given node up to the root node. We thus expect the insertion and deletion routines to keep track of the path they followed from the root down to the leaf node they had to insert or delete. See the avlRebalance routine for more details about this, and the avlInsert and avlDelete routines for reference implementations. It is an implementation goal to allow the creation of AVL trees containing some various data types in their nodes. However, the searching, insertion, and deletion routines needs to be able to compare two data nodes, so they are dependant upon the precise type of the search keys. The implementation of avlSearch, avlInsert and avlDelete uses a user-provided function that compares a tree node with a value and returns -1, 0 or 1 depending if this value is inferior, equal or superior to the key of the tree node. The value that is passed to this comparison function is typed as a GENERIC_ARGUMENT, which is a C union of an integer and a void pointer, thus making argument passing both fast and generic. INTERNAL For cases where execution speed is more important than code size, one could also use his own specialized routines instead of avlInsert, avlDelete and/or avlSearch, where the comparison function would be hardcoded to suit the user's needs. If one decides to do so, he can still use the generic avlRebalance routine because thisone does not needs to use a comparison function. INCLUDE FILE: avlLib.h */ /* includes */ #include <vxWorks.h> #include <stdlib.h> #include <stdio.h> #include "avlLib.h" /* typedefs */ typedef struct { AVL_NODE avl; UINT key; } AVL_UNSIGNED_NODE; /* defines */ #define AVL_MAX_HEIGHT 42 /* The meaning of life, the universe and everything. Plus, the nodes for a tree this high would use more than 2**32 bytes anyway */ /******************************************************************************* * * avlRebalance - make sure the tree conforms to the AVL balancing rules, while * preserving the ordering of the binary tree * * INTERNAL * The AVL tree balancing rules are as follows : * - the height of the left and right subtrees under a given node must never * differ by more than one * - the height of a given subtree is defined as 1 plus the maximum height of * the subtrees under his root node * * The avlRebalance procedure must be called after a leaf node has been inserted * or deleted from the tree. It checks that the AVL balancing rules are * respected, makes local adjustments to the tree if necessary, recalculates * the height field of the modified nodes, and repeats the process for every * node up to the root node. This iteration is necessary because the balancing * rules for a given node might have been broken by the modification we did on * one of the subtrees under it. * * Because we need to iterate the process up to the root node, and the tree * nodes does not contain pointers to their father node, we ask the caller of * this procedure to keep a list of all the nodes traversed from the root node * to the node just before the recently inserted or deleted node. This is the * <ancestors> argument. Because each subtree might have to be re-rooted in the * balancing operation, <ancestors> is actually a list pointers to the node * pointers - thus if re-rooting occurs, the node pointers can be modified so * that they keep pointing to the root of a given subtree. * * <count> is simply a count of elements in the <ancestors> list. * * RETURNS: N/A */ void avlRebalance ( AVL_NODE *** ancestors, /* list of pointers to the ancestor node pointers */ int count /* number ancestors to rebalance */ ) { while (count > 0) { AVL_NODE ** nodepp; /* address of the pointer to the root node of the current subtree */ AVL_NODE * nodep; /* points to root node of current subtree */ AVL_NODE * leftp; /* points to root node of left subtree */ int lefth; /* height of the left subtree */ AVL_NODE * rightp; /* points to root node of right subtree */ int righth; /* height of the right subtree */ /* * Find the current root node and its two subtrees. By construction, * we know that both of them conform to the AVL balancing rules. */ nodepp = ancestors[--count]; nodep = *nodepp; leftp = nodep->left; lefth = (leftp != NULL) ? leftp->height : 0; rightp = nodep->right; righth = (rightp != NULL) ? rightp->height : 0; if (righth - lefth < -1) { /* * * * / \ * n+2 n * * The current subtree violates the balancing rules by beeing too * high on the left side. We must use one of two different * rebalancing methods depending on the configuration of the left * subtree. * * Note that leftp cannot be NULL or we would not pass there ! */ AVL_NODE * leftleftp; /* points to root of left left subtree */ AVL_NODE * leftrightp; /* points to root of left right subtree */ int leftrighth; /* height of left right subtree */ leftleftp = leftp->left; leftrightp = leftp->right; leftrighth = (leftrightp != NULL) ? leftrightp->height : 0; if ((leftleftp != NULL) && (leftleftp->height >= leftrighth)) { /* * <D> <B> * * n+2|n+3 * / \ / \ * <B> <E> ----> <A> <D> * n+2 n n+1 n+1|n+2 * / \ / \ * <A> <C> <C> <E> * n+1 n|n+1 n|n+1 n */ nodep->left = leftrightp; /* D.left = C */ nodep->height = leftrighth + 1; leftp->right = nodep; /* B.right = D */ leftp->height = leftrighth + 2; *nodepp = leftp; /* B becomes root */ } else { /* * <F> * * * / \ <D> * <B> <G> n+2 * n+2 n / \ * / \ ----> <B> <F> * <A> <D> n+1 n+1 * n n+1 / \ / \ * / \ <A> <C> <E> <G> * <C> <E> n n|n-1 n|n-1 n * n|n-1 n|n-1 * * We can assume that leftrightp is not NULL because we expect * leftp and rightp to conform to the AVL balancing rules. * Note that if this assumption is wrong, the algorithm will * crash here. */ leftp->right = leftrightp->left; /* B.right = C */ leftp->height = leftrighth; nodep->left = leftrightp->right; /* F.left = E */ nodep->height = leftrighth; leftrightp->left = leftp; /* D.left = B */ leftrightp->right = nodep; /* D.right = F */ leftrightp->height = leftrighth + 1; *nodepp = leftrightp; /* D becomes root */ } } else if (righth - lefth > 1) { /* * * * / \ * n n+2 * * The current subtree violates the balancing rules by beeing too * high on the right side. This is exactly symmetric to the * previous case. We must use one of two different rebalancing * methods depending on the configuration of the right subtree. * * Note that rightp cannot be NULL or we would not pass there ! */ AVL_NODE * rightleftp; /* points to the root of right left subtree */ int rightlefth; /* height of right left subtree */ AVL_NODE * rightrightp; /* points to the root of right right subtree */ rightleftp = rightp->left; rightlefth = (rightleftp != NULL) ? rightleftp->height : 0; rightrightp = rightp->right; if ((rightrightp != NULL) && (rightrightp->height >= rightlefth)) { /* <B> <D> * * n+2|n+3 * / \ / \ * <A> <D> ----> <B> <E> * n n+2 n+1|n+2 n+1 * / \ / \ * <C> <E> <A> <C> * n|n+1 n+1 n n|n+1 */ nodep->right = rightleftp; /* B.right = C */ nodep->height = rightlefth + 1; rightp->left = nodep; /* D.left = B */ rightp->height = rightlefth + 2; *nodepp = rightp; /* D becomes root */ } else { /* <B> * * * / \ <D> * <A> <F> n+2 * n n+2 / \ * / \ ----> <B> <F> * <D> <G> n+1 n+1 * n+1 n / \ / \ * / \ <A> <C> <E> <G> * <C> <E> n n|n-1 n|n-1 n * n|n-1 n|n-1 * * We can assume that rightleftp is not NULL because we expect * leftp and rightp to conform to the AVL balancing rules. * Note that if this assumption is wrong, the algorithm will * crash here. */ nodep->right = rightleftp->left; /* B.right = C */ nodep->height = rightlefth; rightp->left = rightleftp->right; /* F.left = E */ rightp->height = rightlefth; rightleftp->left = nodep; /* D.left = B */ rightleftp->right = rightp; /* D.right = F */ rightleftp->height = rightlefth + 1; *nodepp = rightleftp; /* D becomes root */ } } else { /* * No rebalancing, just set the tree height * * If the height of the current subtree has not changed, we can * stop here because we know that we have not broken the AVL * balancing rules for our ancestors. */ int height; height = ((righth > lefth) ? righth : lefth) + 1; if (nodep->height == height) break; nodep->height = height; } } } /******************************************************************************* * * avlSearch - search a node in an AVL tree * * At the time of the call, <root> is the root node pointer. <key> is the value * we want to search, and <compare> is the user-provided comparison function. * * Note that we cannot have several nodes with the equal keys in the tree, so * there is no ambiguity about which node will be found. * * Also note that the search procedure does not depend on the tree balancing * rules, but because the tree is balanced, we know that the search procedure * will always be efficient. * * RETURNS: pointer to the node whose key equals <key>, or NULL if there is * no such node in the tree */ void * avlSearch ( AVL_TREE root, /* root node pointer */ GENERIC_ARGUMENT key, /* search key */ int compare (void *, GENERIC_ARGUMENT) /* comparison function */ ) { AVL_NODE * nodep; /* pointer to the current node */ nodep = root; while (1) { int delta; /* result of the comparison operation */ if (nodep == NULL) return NULL; /* not found ! */ delta = compare (nodep, key); if (0 == delta) return nodep; /* found the node */ else if (delta < 0) nodep = nodep->left; else nodep = nodep->right; } } /******************************************************************************* * * avlSearchUnsigned - search a node in an AVL tree * * This is a specialized implementation of avlSearch for cases where the * node to be searched is an AVL_UNSIGNED_NODE. * * RETURNS: pointer to the node whose key equals <key>, or NULL if there is * no such node in the tree */ void * avlSearchUnsigned ( AVL_TREE root, /* root node pointer */ UINT key /* search key */ ) { AVL_UNSIGNED_NODE * nodep; /* pointer to the current node */ nodep = (AVL_UNSIGNED_NODE *) root; while (1) { if (nodep == NULL) return NULL; /* not found ! */ if (key == nodep->key) return nodep; /* found the node */ else if (key < nodep->key) nodep = nodep->avl.left; else nodep = nodep->avl.right; } } /******************************************************************************* * * avlInsert - insert a node in an AVL tree * * At the time of the call, <root> points to the root node pointer. This root * node pointer is possibly NULL if the tree is empty. <newNode> points to the * node we want to insert. His left, right and height fields need not be filled, * but the user will probably have added his own data fields after those. <key> * is newNode's key, that will be passed to the comparison function. This is * redundant because it could really be derived from newNode, but the way to do * this depends on the precise type of newNode so we cannot do this in a generic * routine. <compare> is the user-provided comparison function. * * Note that we cannot have several nodes with the equal keys in the tree, so * the insertion operation will fail if we try to insert a node that has a * duplicate key. * * Also note that because we keep the tree balanced, the root node pointer that * is pointed by the <root> argument can be modified in this function. * * INTERNAL * The insertion routine works just like in a non-balanced binary tree : we * walk down the tree like if we were searching a node, and when we reach a leaf * node we insert newNode at this position. * * Because the balancing procedure needs to be able to walk back to the root * node, we keep a list of pointers to the pointers we followed on our way down * the tree. * * RETURNS: OK, or ERROR if the tree already contained a node with the same key */ STATUS avlInsert ( AVL_TREE * root, /* pointer to the root node ptr */ void * newNode, /* ptr to the node we want to insert */ GENERIC_ARGUMENT key, /* search key of newNode */ int compare (void *, GENERIC_ARGUMENT) /* comparison function */ ) { AVL_NODE ** nodepp; /* ptr to current node ptr */ AVL_NODE ** ancestor[AVL_MAX_HEIGHT]; /* list of pointers to all our ancestor node ptrs */ int ancestorCount; /* number of ancestors */ nodepp = root; ancestorCount = 0; while (1) { AVL_NODE * nodep; /* pointer to the current node */ int delta; /* result of the comparison operation */ nodep = *nodepp; if (nodep == NULL) break; /* we can insert a leaf node here ! */ ancestor[ancestorCount++] = nodepp; delta = compare (nodep, key); if (0 == delta) return ERROR; else if (delta < 0) nodepp = (AVL_NODE **)&(nodep->left); else nodepp = (AVL_NODE **)&(nodep->right); } ((AVL_NODE *)newNode)->left = NULL; ((AVL_NODE *)newNode)->right = NULL; ((AVL_NODE *)newNode)->height = 1; *nodepp = newNode; avlRebalance (ancestor, ancestorCount); return OK; } /******************************************************************************* * * avlInsertUnsigned - insert a node in an AVL tree * * This is a specialized implementation of avlInsert for cases where the * node to be inserted is an AVL_UNSIGNED_NODE. * * RETURNS: OK, or ERROR if the tree already contained a node with the same key */ STATUS avlInsertUnsigned ( AVL_TREE * root, /* pointer to the root node ptr */ void * newNode /* ptr to the node we want to insert */ ) { AVL_UNSIGNED_NODE ** nodepp; /* ptr to current node ptr */ AVL_UNSIGNED_NODE ** ancestor[AVL_MAX_HEIGHT]; /* list of pointers to all our ancestor node ptrs */ int ancestorCount; /* number of ancestors */ UINT key; key = ((AVL_UNSIGNED_NODE *)newNode)->key; nodepp = (AVL_UNSIGNED_NODE **) root; ancestorCount = 0; while (1) { AVL_UNSIGNED_NODE * nodep; /* pointer to the current node */ nodep = *nodepp; if (nodep == NULL) break; /* we can insert a leaf node here ! */ ancestor[ancestorCount++] = nodepp; if (key == nodep->key) return ERROR; else if (key < nodep->key) nodepp = (AVL_UNSIGNED_NODE **)&(nodep->avl.left); else nodepp = (AVL_UNSIGNED_NODE **)&(nodep->avl.right); } ((AVL_NODE *)newNode)->left = NULL; ((AVL_NODE *)newNode)->right = NULL; ((AVL_NODE *)newNode)->height = 1; *nodepp = newNode; avlRebalance ((AVL_NODE ***)ancestor, ancestorCount); return OK; } /******************************************************************************* * * avlDelete - delete a node in an AVL tree * * At the time of the call, <root> points to the root node pointer and * <key> is the key of the node we want to delete. <compare> is the * user-provided comparison function. * * The deletion operation will of course fail if the desired node was not * already in the tree. * * Also note that because we keep the tree balanced, the root node pointer that * is pointed by the <root> argument can be modified in this function. * * On exit, the node is removed from the AVL tree but it is not free()'d. * * INTERNAL * The deletion routine works just like in a non-balanced binary tree : we * walk down the tree like searching the node we have to delete. When we find * it, if it is not a leaf node, we have to replace it with a leaf node that * has an adjacent key. Then the rebalancing operation will have to enforce the * balancing rules by walking up the path from the leaf node that got deleted * or moved. * * Because the balancing procedure needs to be able to walk back to the root * node, we keep a list of pointers to the pointers we followed on our way down * the tree. * * RETURNS: pointer to the node we deleted, or NULL if the tree does not * contain any such node */ void * avlDelete ( AVL_TREE * root, /* pointer to the root node pointer */ GENERIC_ARGUMENT key, /* search key of node we want to delete */ int compare (void *, GENERIC_ARGUMENT) /* comparison function */ ) { AVL_NODE ** nodepp; /* ptr to current node ptr */ AVL_NODE * nodep; /* ptr to the current node */ AVL_NODE ** ancestor[AVL_MAX_HEIGHT]; /* list of pointers to all our ancestor node pointers */ int ancestorCount; /* number of ancestors */ AVL_NODE * deletep; /* ptr to the node we have to delete */ nodepp = root; ancestorCount = 0; while (1) { int delta; /* result of the comparison operation */ nodep = *nodepp; if (nodep == NULL) return NULL; /* node was not in the tree ! */ ancestor[ancestorCount++] = nodepp; delta = compare (nodep, key); if (0 == delta) break; /* we found the node we have to delete */ else if (delta < 0) nodepp = (AVL_NODE **)&(nodep->left); else nodepp = (AVL_NODE **)&(nodep->right); } deletep = nodep; if (nodep->left == NULL) { /* * There is no node on the left subtree of delNode. * Either there is one (and only one, because of the balancing rules) * on its right subtree, and it replaces delNode, or it has no child * nodes at all and it just gets deleted */ *nodepp = nodep->right; /* * we know that nodep->right was already balanced so we don't have to * check it again */ ancestorCount--; } else { /* * We will find the node that is just before delNode in the ordering * of the tree and promote it to delNode's position in the tree. */ AVL_NODE ** deletepp; /* ptr to the ptr to the node we have to delete */ int deleteAncestorCount; /* place where the replacing node will have to be inserted in the ancestor list */ deleteAncestorCount = ancestorCount; deletepp = nodepp; deletep = nodep; /* search for node just before delNode in the tree ordering */ nodepp = (AVL_NODE **)&(nodep->left); while (1) { nodep = *nodepp; if (nodep->right == NULL) break; ancestor[ancestorCount++] = nodepp; nodepp = (AVL_NODE **)&(nodep->right); } /* * this node gets replaced by its (unique, because of balancing rules) * left child, or deleted if it has no childs at all */ *nodepp = nodep->left; /* now this node replaces delNode in the tree */ nodep->left = deletep->left; nodep->right = deletep->right; nodep->height = deletep->height; *deletepp = nodep; /* * We have replaced delNode with nodep. Thus the pointer to the left * subtree of delNode was stored in delNode->left and it is now * stored in nodep->left. We have to adjust the ancestor list to * reflect this. */ ancestor[deleteAncestorCount] = (AVL_NODE **)&(nodep->left); } avlRebalance (ancestor, ancestorCount); return deletep; } /******************************************************************************* * * avlDeleteUnsigned - delete a node in an AVL tree * * This is a specialized implementation of avlDelete for cases where the * node to be deleted is an AVL_UNSIGNED_NODE. * * RETURNS: pointer to the node we deleted, or NULL if the tree does not * contain any such node */ void * avlDeleteUnsigned ( AVL_TREE * root, /* pointer to the root node pointer */ UINT key /* search key of node we want to delete */ ) { AVL_UNSIGNED_NODE ** nodepp; /* ptr to current node ptr */ AVL_UNSIGNED_NODE * nodep; /* ptr to the current node */ AVL_UNSIGNED_NODE ** ancestor[AVL_MAX_HEIGHT]; /* list of pointers to all our ancestor node pointers */ int ancestorCount; /* number of ancestors */ AVL_UNSIGNED_NODE * deletep; /* ptr to the node we have to delete */ nodepp = (AVL_UNSIGNED_NODE **)root; ancestorCount = 0; while (1) { nodep = *nodepp; if (nodep == NULL) return NULL; /* node was not in the tree ! */ ancestor[ancestorCount++] = nodepp; if (key == nodep->key) break; /* we found the node we have to delete */ else if (key < nodep->key) nodepp = (AVL_UNSIGNED_NODE **)&(nodep->avl.left); else nodepp = (AVL_UNSIGNED_NODE **)&(nodep->avl.right); } deletep = nodep; if (nodep->avl.left == NULL) { /* * There is no node on the left subtree of delNode. * Either there is one (and only one, because of the balancing rules) * on its right subtree, and it replaces delNode, or it has no child * nodes at all and it just gets deleted */ *nodepp = nodep->avl.right; /* * we know that nodep->right was already balanced so we don't have to * check it again */ ancestorCount--; } else { /* * We will find the node that is just before delNode in the ordering * of the tree and promote it to delNode's position in the tree. */ AVL_UNSIGNED_NODE ** deletepp; /* ptr to the ptr to the node we have to delete */ int deleteAncestorCount; /* place where the replacing node will have to be inserted in the ancestor list */ deleteAncestorCount = ancestorCount; deletepp = nodepp; deletep = nodep; /* search for node just before delNode in the tree ordering */ nodepp = (AVL_UNSIGNED_NODE **)&(nodep->avl.left); while (1) { nodep = *nodepp; if (nodep->avl.right == NULL) break; ancestor[ancestorCount++] = nodepp; nodepp = (AVL_UNSIGNED_NODE **)&(nodep->avl.right); } /* * this node gets replaced by its (unique, because of balancing rules) * left child, or deleted if it has no childs at all */ *nodepp = nodep->avl.left; /* now this node replaces delNode in the tree */ nodep->avl.left = deletep->avl.left; nodep->avl.right = deletep->avl.right; nodep->avl.height = deletep->avl.height; *deletepp = nodep; /* * We have replaced delNode with nodep. Thus the pointer to the left * subtree of delNode was stored in delNode->left and it is now * stored in nodep->left. We have to adjust the ancestor list to * reflect this. */ ancestor[deleteAncestorCount] = (AVL_UNSIGNED_NODE **)&(nodep->avl.left); } avlRebalance ((AVL_NODE ***)ancestor, ancestorCount); return deletep; } /******************************************************************************* * * avlSuccessorGet - find node with key successor to input key on an AVL tree * * At the time of the call, <root> is the root node pointer. <key> is the value * we want to search, and <compare> is the user-provided comparison function. * * Note that we cannot have several nodes with the equal keys in the tree, so * there is no ambiguity about which node will be found. * * Also note that the search procedure does not depend on the tree balancing * rules, but because the tree is balanced, we know that the search procedure * will always be efficient. * * RETURNS: pointer to the node whose key is the immediate successor of <key>, * or NULL if there is no such node in the tree */ void * avlSuccessorGet ( AVL_TREE root, /* root node pointer */ GENERIC_ARGUMENT key, /* search key */ int compare (void *, GENERIC_ARGUMENT) /* comparison function */ ) { AVL_NODE * nodep; /* pointer to the current node */ AVL_NODE * superiorp; /* pointer to the current superior*/ nodep = root; superiorp = NULL; while (1) { int delta; /* result of the comparison operation */ if (nodep == NULL) return superiorp; delta = compare (nodep, key); if (delta < 0) { superiorp = nodep; /* update superiorp */ nodep = nodep->left; } else nodep = nodep->right; } } /******************************************************************************* * * avlPredecessorGet - find node with key predecessor to input key on an AVL tree * * At the time of the call, <root> is the root node pointer. <key> is the value * we want to search, and <compare> is the user-provided comparison function. * * Note that we cannot have several nodes with the equal keys in the tree, so * there is no ambiguity about which node will be found. * * Also note that the search procedure does not depend on the tree balancing * rules, but because the tree is balanced, we know that the search procedure * will always be efficient. * * RETURNS: pointer to the node whose key is the immediate predecessor of <key>, * or NULL if there is no such node in the tree */ void * avlPredecessorGet ( AVL_TREE root, /* root node pointer */ GENERIC_ARGUMENT key, /* search key */ int compare (void *, GENERIC_ARGUMENT) /* comparison function */ ) { AVL_NODE * nodep; /* pointer to the current node */ AVL_NODE * inferiorp; /* pointer to the current inferior*/ nodep = root; inferiorp = NULL; while (1) { int delta; /* result of the comparison operation */ if (nodep == NULL) return inferiorp; delta = compare (nodep, key); if (delta > 0) { inferiorp = nodep; /* update inferiorp */ nodep = nodep->right; } else nodep = nodep->left; } } /******************************************************************************* * * avlMinimumGet - find node with minimum key * * At the time of the call, <root> is the root node pointer. <key> is the value * we want to search, and <compare> is the user-provided comparison function. * * RETURNS: pointer to the node with minimum key; NULL if the tree is empty */ void * avlMinimumGet ( AVL_TREE root /* root node pointer */ ) { if (NULL == root) return NULL; while (root->left != NULL) { root = root->left; } return root; } /******************************************************************************* * * avlMaximumGet - find node with maximum key * * At the time of the call, <root> is the root node pointer. <key> is the value * we want to search, and <compare> is the user-provided comparison function. * * RETURNS: pointer to the node with maximum key; NULL if the tree is empty */ void * avlMaximumGet ( AVL_TREE root /* root node pointer */ ) { if (NULL == root) return NULL; while (root->right != NULL) { root = root->right; } return root; } /******************************************************************************* * * avlInsertInform - insert a node in an AVL tree and report key holder * * At the time of the call, <pRoot> points to the root node pointer. This root * node pointer is possibly NULL if the tree is empty. <pNewNode> points to the * node we want to insert. His left, right and height fields need not be filled, * but the user will probably have added his own data fields after those. <key> * is newNode's key, that will be passed to the comparison function. This is * redundant because it could really be derived from newNode, but the way to do * this depends on the precise type of newNode so we cannot do this in a generic * routine. <compare> is the user-provided comparison function. * * Note that we cannot have several nodes with the equal keys in the tree, so * the insertion operation will fail if we try to insert a node that has a * duplicate key. However, if the <replace> boolean is set to true then in * case of conflict we will remove the old node, we will put in its position the * new one, and we will return the old node pointer in the postion pointed by * <ppReplacedNode>. * * Also note that because we keep the tree balanced, the root node pointer that * is pointed by the <pRoot> argument can be modified in this function. * * INTERNAL * The insertion routine works just like in a non-balanced binary tree : we * walk down the tree like if we were searching a node, and when we reach a leaf * node we insert newNode at this position. * * Because the balancing procedure needs to be able to walk back to the root * node, we keep a list of pointers to the pointers we followed on our way down * the tree. * * RETURNS: OK, or ERROR if the tree already contained a node with the same key * and replacement was not allowed. In both cases it will place a pointer to * the key holder in the position pointed by <ppKeyHolder>. */ STATUS avlInsertInform ( AVL_TREE * pRoot, /* ptr to the root node pointer */ void * pNewNode, /* pointer to the candidate node */ GENERIC_ARGUMENT key, /* unique key of new node */ void ** ppKeyHolder, /* ptr to final key holder */ int compare (void *, GENERIC_ARGUMENT) /* comparison function */ ) { AVL_NODE ** nodepp; /* ptr to current node ptr */ AVL_NODE ** ancestor[AVL_MAX_HEIGHT]; /* list of pointers to all our ancestor node ptrs */ int ancestorCount; /* number of ancestors */ if (NULL == ppKeyHolder) { printf("invalid input data were passed to avlInsertInform\n"); return ERROR; }; nodepp = pRoot; ancestorCount = 0; while (1) { AVL_NODE * nodep; /* pointer to the current node */ int delta; /* result of the comparison operation */ nodep = *nodepp; if (nodep == NULL) break; /* we can insert a leaf node here ! */ ancestor[ancestorCount++] = nodepp; delta = compare (nodep, key); if (0 == delta) { /* we inform the caller of the key holder node and return ERROR */ *ppKeyHolder = nodep; return ERROR; } else if (delta < 0) nodepp = (AVL_NODE **)&(nodep->left); else nodepp = (AVL_NODE **)&(nodep->right); } ((AVL_NODE *)pNewNode)->left = NULL; ((AVL_NODE *)pNewNode)->right = NULL; ((AVL_NODE *)pNewNode)->height = 1; *nodepp = pNewNode; *ppKeyHolder = pNewNode; avlRebalance (ancestor, ancestorCount); return OK; } /******************************************************************************* * * avlRemoveInsert - forcefully insert a node in an AVL tree * * At the time of the call, <pRoot> points to the root node pointer. This root * node pointer is possibly NULL if the tree is empty. <pNewNode> points to the * node we want to insert. His left, right and height fields need not be filled, * but the user will probably have added his own data fields after those. <key> * is newNode's key, that will be passed to the comparison function. This is * redundant because it could really be derived from newNode, but the way to do * this depends on the precise type of newNode so we cannot do this in a generic * routine. <compare> is the user-provided comparison function. * * Note that we cannot have several nodes with the equal keys in the tree, so * the insertion operation will fail if we try to insert a node that has a * duplicate key. However, in case of conflict we will remove the old node, we * will put in its position the new one, and we will return the old node pointer * * Also note that because we keep the tree balanced, the root node pointer that * is pointed by the <pRoot> argument can be modified in this function. * * INTERNAL * The insertion routine works just like in a non-balanced binary tree : we * walk down the tree like if we were searching a node, and when we reach a leaf * node we insert newNode at this position. * * Because the balancing procedure needs to be able to walk back to the root * node, we keep a list of pointers to the pointers we followed on our way down * the tree. * * RETURNS: NULL if insertion was carried out without replacement, or if * replacement occured the pointer to the replaced node * */ void * avlRemoveInsert ( AVL_TREE * pRoot, /* ptr to the root node pointer */ void * pNewNode, /* pointer to the candidate node */ GENERIC_ARGUMENT key, /* unique key of new node */ int compare (void *, GENERIC_ARGUMENT) /* comparison function */ ) { AVL_NODE ** nodepp; /* ptr to current node ptr */ AVL_NODE ** ancestor[AVL_MAX_HEIGHT]; /* list of pointers to all our ancestor node ptrs */ int ancestorCount; /* number of ancestors */ nodepp = pRoot; ancestorCount = 0; while (1) { AVL_NODE * nodep; /* pointer to the current node */ int delta; /* result of the comparison operation */ nodep = *nodepp; if (nodep == NULL) break; /* we can insert a leaf node here ! */ ancestor[ancestorCount++] = nodepp; delta = compare (nodep, key); if (0 == delta) { /* we copy the tree data from the old node to the new node */ ((AVL_NODE *)pNewNode)->left = nodep->left; ((AVL_NODE *)pNewNode)->right = nodep->right; ((AVL_NODE *)pNewNode)->height = nodep->height; /* and we make the new node child of the old node's parent */ *nodepp = pNewNode; /* before we return it we sterilize the old node */ nodep->left = NULL; nodep->right = NULL; nodep->height = 1; return nodep; } else if (delta < 0) nodepp = (AVL_NODE **)&(nodep->left); else nodepp = (AVL_NODE **)&(nodep->right); } ((AVL_NODE *)pNewNode)->left = NULL; ((AVL_NODE *)pNewNode)->right = NULL; ((AVL_NODE *)pNewNode)->height = 1; *nodepp = pNewNode; avlRebalance (ancestor, ancestorCount); return NULL; } /******************************************************************************* * * avlTreeWalk- walk the whole tree and execute a function on each node * * At the time of the call, <pRoot> points to the root node pointer. * * RETURNS: OK always * */ STATUS avlTreeWalk(AVL_TREE * pRoot, void walkExec(AVL_TREE * ppNode)) { if ((NULL == pRoot) || (NULL == *pRoot)) { return OK; }; if (!(NULL == (*pRoot)->left)) { avlTreeWalk((AVL_TREE *)(&((*pRoot)->left)), walkExec); } if (!(NULL == (*pRoot)->right)) { avlTreeWalk((AVL_TREE *)(&((*pRoot)->right)), walkExec); } walkExec(pRoot); return OK; } STATUS avlTreeWalkWithPara(AVL_TREE * pRoot, void walkExec(AVL_TREE * ppNode, void * v_Para), void * v_Para) { if ((NULL == pRoot) || (NULL == *pRoot)) { return OK; }; if (!(NULL == (*pRoot)->left)) { avlTreeWalkWithPara((AVL_TREE *)(&((*pRoot)->left)), walkExec, v_Para); } if (!(NULL == (*pRoot)->right)) { avlTreeWalkWithPara((AVL_TREE *)(&((*pRoot)->right)), walkExec, v_Para); } walkExec(pRoot, v_Para); return OK; } /******************************************************************************* * * avlTreePrint- print the whole tree * * At the time of the call, <pRoot> points to the root node pointer. * * RETURNS: OK always * */ STATUS avlTreePrint(AVL_TREE * pRoot, void printNode(void * nodep)) { if ((NULL == pRoot) || (NULL == *pRoot)) { return OK; }; printNode(*pRoot); if (!(NULL == (*pRoot)->left)) { avlTreePrint((AVL_TREE *)(&((*pRoot)->left)), printNode); } if (!(NULL == (*pRoot)->right)) { avlTreePrint((AVL_TREE *)(&((*pRoot)->right)), printNode); } return OK; } /******************************************************************************* * * avlTreeErase - erase the whole tree * * At the time of the call, <pRoot> points to the root node pointer. * Unlike the avlDelete routine here we do perform memory management * ASSUMING that all nodes carry shallow data only. Otherwise we should * use avlTreeWalk with the appropriate walkExec memory freeing function. * Since we do not plan to reuse the tree intermediate rebalancing is not needed. * * RETURNS: OK always * */ STATUS avlTreeErase(AVL_TREE * pRoot) { if ((NULL == pRoot) || (NULL == *pRoot)) { return OK; }; if (!(NULL == (*pRoot)->left)) { avlTreeErase((AVL_TREE *)(&((*pRoot)->left))); } if (!(NULL == (*pRoot)->right)) { avlTreeErase((AVL_TREE *)(&((*pRoot)->right))); } free(*pRoot); *pRoot = NULL; return OK; } #ifndef AVLTREE_FREE_FUNC_DEFINED #define AVLTREE_FREE_FUNC_DEFINED typedef void (*AVLTREE_FREE_FUNC)(void *); #endif STATUS avlTreeEraseWithFunc(AVL_TREE * pRoot, AVLTREE_FREE_FUNC v_Func) { if ((NULL == pRoot) || (NULL == *pRoot) || (NULL == v_Func)) { return OK; }; if (!(NULL == (*pRoot)->left)) { avlTreeEraseWithFunc((AVL_TREE *)(&((*pRoot)->left)), v_Func); } if (!(NULL == (*pRoot)->right)) { avlTreeEraseWithFunc((AVL_TREE *)(&((*pRoot)->right)), v_Func); } v_Func(*pRoot); *pRoot = NULL; return OK; } /******************************************************************************* * * avlTreePrintErase - erase the whole tree assuming that all nodes were * created using malloc. * * At the time of the call, <pRoot> points to the root node pointer. * Unlike the avlDelete routine here we do perform memory management. * Since we do not plan to reuse the tree intermediate rebalancing is not needed. * * RETURNS: OK always and assigns NULL to *pRoot. * */ STATUS avlTreePrintErase(AVL_TREE * pRoot, void printNode(void * nodep)) { if ((NULL == pRoot) || (NULL == *pRoot)) { return OK; }; printNode(*pRoot); if (!(NULL == (*pRoot)->left)) { avlTreePrintErase((AVL_TREE *)(&((*pRoot)->left)), printNode); free((*pRoot)->left); (*pRoot)->left = NULL; } if (!(NULL == (*pRoot)->right)) { avlTreePrintErase((AVL_TREE *)(&((*pRoot)->right)), printNode); free((*pRoot)->right); (*pRoot)->right = NULL; } free(*pRoot); *pRoot = NULL; return OK; }