AVL树C语言完整实现

AVL树的介绍见http://blog.csdn.net/pngynghay/article/details/22443525，本文给出的是AVL树的一种实现。

采用非递归方式，效率较好，经过常规测试。

 

#include <stdio.h>#include <string.h>#include <stdlib.h>#include <errno.h>#include <assert.h>typedef enum{EH = 0,LH = 1,RH = -1}bh_t;typedef enum{FALSE = 0,TRUE = 1}bool_t;typedef int ElemType;typedef struct BSTNode{ElemType key;int bf;struct BSTNode *lchild,*rchild,*parent;}BSTNode,*BSTree;bool_t  searchAVL(BSTree root,ElemType key, BSTNode **parent){BSTNode *tmp = NULL;assert(root != NULL);*parent = root->parent;tmp = root;while(NULL != tmp){if(tmp->key == key){return TRUE;}*parent = tmp;if(tmp->key > key){tmp = tmp->lchild;}else{tmp = tmp->rchild;}}return FALSE;}/* get the minimum node*/BSTNode* minNode(BSTNode* root){if (root == NULL){return NULL;}while (root->lchild != NULL){root = root->lchild;}return root;}/* get the maximum node*/BSTNode* maxNode(BSTNode* root){if (root == NULL){return NULL;}while (root->rchild != NULL){root = root->rchild;}return root;}/* get the previous node*/BSTNode* preNode(BSTNode* target){if (target == NULL){return NULL;}if (target->lchild != NULL){return maxNode(target->lchild);}while ((target->parent!=NULL) && (target!=target->parent->rchild)){target = target->parent;}return target->parent;}/* get the next node*/BSTNode* nextNode(BSTNode* target){if (target == NULL){return NULL;}if (target->rchild != NULL){return minNode(target->rchild);}while ((target->parent!=NULL) && (target!=target->parent->lchild)){target = target->parent;}return target->parent;}BSTNode* leftbalance(BSTNode* root, BSTNode* parent, BSTNode* child){BSTNode *cur;assert((parent != NULL)&&(child != NULL));/* LR */if (child->bf == RH){cur = child->rchild;cur->parent = parent->parent;child->rchild = cur->lchild;if (cur->lchild != NULL){cur->lchild->parent = child;}parent->lchild = cur->rchild;if (cur->rchild != NULL){cur->rchild->parent = parent;}cur->lchild = child;cur->rchild = parent;child->parent = cur;if (parent->parent != NULL){if (parent->parent->lchild == parent){parent->parent->lchild = cur;}else {parent->parent->rchild = cur;}}else{root = cur;}parent->parent = cur;if (cur->bf == EH){parent->bf = EH;child->bf = EH;}else if (cur->bf == RH){parent->bf = EH;child->bf = LH;}else{parent->bf = RH;child->bf = EH;}cur->bf = EH;}/* LL */else {child->parent = parent->parent;parent->lchild = child->rchild;if (child->rchild != NULL){child->rchild->parent = parent;}child->rchild = parent;if (parent->parent != NULL){if (parent->parent->lchild == parent){parent->parent->lchild = child;}else {parent->parent->rchild = child;}}else{root = child;}parent->parent = child;/* when insert */if (child->bf == LH) {child->bf = EH;parent->bf = EH;}/* when delete*/else {child->bf = RH;parent->bf = LH;}}return root;}BSTNode* rightbalance(BSTNode* root, BSTNode* parent, BSTNode* child){BSTNode *cur;assert((parent != NULL)&&(child != NULL));/* RL */if (child->bf == LH) {cur = child->lchild;cur->parent = parent->parent;child->lchild = cur->rchild;if (cur->rchild != NULL){cur->rchild->parent = child;}parent->rchild = cur->lchild;if (cur->lchild != NULL){cur->lchild->parent = parent;}cur->lchild = parent;cur->rchild = child;child->parent = cur;if (parent->parent != NULL){if (parent->parent->lchild == parent){parent->parent->lchild = cur;}else{parent->parent->rchild = cur;}}else{root = cur;}parent->parent = cur;if (cur->bf == EH){parent->bf = EH;child->bf = EH;}else if (cur->bf == LH){parent->bf = EH;child->bf = RH;}else{parent->bf = LH;child->bf = EH;}cur->bf = EH;}/* RR */else {child->parent = parent->parent;parent->rchild = child->lchild;if (child->lchild != NULL)child->lchild->parent = parent;child->lchild = parent;if (parent->parent != NULL){if (parent->parent->lchild == parent){parent->parent->lchild = child;}else{parent->parent->rchild = child;}}else{root = child;}parent->parent = child;/* when insert */if (child->bf == RH) {child->bf = EH;parent->bf = EH;}/* when delete*/else{child->bf = LH;parent->bf = RH;}}return root;}BSTNode* insertNode(ElemType key, BSTNode* root){BSTNode *parent = NULL, *cur = NULL, *child = NULL;assert (root != NULL);/* node exists*/if (searchAVL(root,key,&parent)){return root;}cur = (BSTNode*)malloc(sizeof(BSTNode));cur->parent = parent;cur->key = key;cur->lchild = NULL;cur->rchild = NULL;cur->bf = EH;if (key<parent->key){parent->lchild = cur;child = parent->lchild;}else{parent->rchild = cur;child = parent->rchild;}/*get the minimax tree needed to be adjusted*/while ((parent != NULL)) {if (child == parent->lchild){if (parent->bf == RH){parent->bf = EH;return root;}else if (parent->bf == EH){root = leftbalance(root, parent, child);break;}else{parent->bf = LH;child = parent;parent = parent->parent;}}else{if (parent->bf == LH) //是右孩子，不会引起不平衡{parent->bf = EH;return root;}else if (parent->bf == RH) //是右孩子，并且引起parent的不平衡{root = rightbalance(root, parent, child);break;}else //是右孩子，并且可能引起parent的parent的不平衡{parent->bf = RH;child = parent;parent = parent->parent;}}}return root;}BSTNode* deleteNode(ElemType key, BSTNode* root){BSTNode *dNode=NULL, *parent=NULL, *child = NULL;ElemType temp;assert(root!=NULL);if (!searchAVL(root,key,&parent)){return root;}if (parent == NULL){dNode = root;}else if ((parent->lchild!=NULL)&&(parent->lchild->key==key)){dNode = parent->lchild;}else {dNode = parent->rchild;}child = dNode;while ((child->lchild!=NULL)||(child->rchild!=NULL)) //确定需要删除的结点{if (child->bf == LH){child = preNode(dNode);}else {child = nextNode(dNode);}temp = child->key;child->key = dNode->key;dNode->key = temp;dNode = child;}child = dNode;parent = dNode->parent;while ((parent != NULL)) //查找需要调整的最小子树{if (child == parent->lchild){if (parent->bf == LH){parent->bf = EH;child = parent;parent = parent->parent;}else if (parent->bf == RH){child = parent->rchild;root = rightbalance(root, parent, child);break;}else{parent->bf = RH;break;}}else{if (parent->bf == RH){parent->bf = EH;child = parent;parent = parent->parent;}else if (parent->bf == LH){child = parent->lchild;root = leftbalance(root, parent, child);break;}else {parent->bf = LH;break;}}}if (dNode->parent != NULL){if (dNode == dNode->parent->lchild){dNode->parent->lchild = NULL;}else {dNode->parent->rchild = NULL;}}free(dNode);dNode = NULL;if (root == dNode){root = NULL; //root被删除, 避免野指针}return root;}BSTNode* createAVL(int *data, int size){int i, j;BSTNode *root;if (size<1){return NULL;}root = (BSTNode*)malloc(sizeof(BSTNode));root->parent = NULL;root->lchild = NULL;root->rchild = NULL;root->key = data[0];root->bf = 0;for(i=1;i<size;i++)root = insertNode(data[i], root);return root;}void destroyAVL(BSTNode* root){if (root != NULL){destroyAVL(root->lchild);destroyAVL(root->rchild);free(root);root=NULL;}}void InOrderTraverse(BSTree root){if(NULL != root){InOrderTraverse(root->lchild);printf("%d\t",root->key);InOrderTraverse(root->rchild);}}void PreOrderTraverse(BSTree root){if(NULL != root){printf("%d\t",root->key);PreOrderTraverse(root->lchild);PreOrderTraverse(root->rchild);}}int main(int argc, char *argv[]){int data[] = {1, 5, 7, 4, 3, 2, 11, 9, 10,100};BSTNode* root;root = createAVL(data, sizeof(data)/sizeof(data[0]));printf("\n++++++++++++++++++++++++++++\n");InOrderTraverse(root);printf("\n");PreOrderTraverse(root);root = deleteNode(5, root);printf("\n++++++++delete 5++++++++++\n");InOrderTraverse(root);printf("\n");PreOrderTraverse(root);root = deleteNode(3, root);printf("\n++++++++delete 3++++++++++\n");InOrderTraverse(root);printf("\n");PreOrderTraverse(root);root = deleteNode(1, root);printf("\n++++++++delete 1++++++++++\n");InOrderTraverse(root);printf("\n");PreOrderTraverse(root);root = deleteNode(7, root);printf("\n++++++++delete 7++++++++++\n");InOrderTraverse(root);printf("\n");PreOrderTraverse(root);root = deleteNode(4, root);printf("\n++++++++delete 4++++++++++\n");InOrderTraverse(root);printf("\n");PreOrderTraverse(root);root = deleteNode(2, root);printf("\n++++++++delete 2++++++++++\n");InOrderTraverse(root);printf("\n");PreOrderTraverse(root);printf("\n");destroyAVL(root);}