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AVL.c
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AVL.c
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#include <stdio.h>
#include <stdlib.h>
typedef struct avlTreeNode {
int key;
struct avlTreeNode* leftNode;
struct avlTreeNode* rightNode;
}avlTreeNode;
avlTreeNode* LL_rotate(avlTreeNode* parent) {
avlTreeNode* child = parent->leftNode;
parent->leftNode = child->rightNode;
child->rightNode = parent;
return child;
}
avlTreeNode* RR_rotate(avlTreeNode* parent) {
avlTreeNode* child = parent->rightNode;
parent->rightNode = child->leftNode;
child->leftNode = parent;
return child;
}
avlTreeNode* LR_rotate(avlTreeNode* parent) {
avlTreeNode* child = parent->leftNode;
parent->leftNode = RR_rotate(child);
return LL_rotate(parent);
}
avlTreeNode* RL_rotate(avlTreeNode* parent) {
avlTreeNode* child = parent->rightNode;
parent->rightNode = LL_rotate(child);
return RR_rotate(parent);
}
int getHeightOfSubTree(avlTreeNode* ptr) {
int height = 0;
if (ptr != NULL) {
height = MAX(getHeightOfSubTree(ptr->leftNode), getHeightOfSubTree(ptr->rightNode)) + 1;
}
return height;
}
int getBalanceFactor(avlTreeNode* ptr) {
if (ptr == NULL) {
return 0;
}
return getHeightOfSubTree(ptr->leftNode) - getHeightOfSubTree(ptr->rightNode);
}
avlTreeNode* rebalanceTree(avlTreeNode** ptr) {
int balanceFactor = getBalanceFactor(*ptr);
if (balanceFactor > 1) {
if (getBalanceFactor((*ptr)->leftNode) > 0) {
*ptr = LL_rotate(*ptr);
}
else {
*ptr = LR_rotate(*ptr);
}
}
else if (balanceFactor < -1) {
if (getBalanceFactor((*ptr)->rightNode) < 0) {
*ptr = RR_rotate(*ptr);
}
else {
*ptr = RL_rotate(*ptr);
}
}
return *ptr;
}