AVL樹

AVL樹模板：https://blog.csdn.net/S_999999/article/details/97409459

後面再來好好解析一下

#include <iostream>
using namespace std;
struct node {
 int val;
 struct node *left, *right;
};
node *rotateLeft(node *root) {
     node *t = root->right;
     root->right = t->left;
     t->left = root;
     return t;
}
node *rotateRight(node *root) {
     node *t = root->left;
     root->left = t->right;
     t->right = root;
     return t;
}
node *rotateLeftRight(node *root) {
     root->left = rotateLeft(root->left);
     return rotateRight(root);
}
node *rotateRightLeft(node *root) {
     root->right = rotateRight(root->right);
     return rotateLeft(root);
}
int  getHeight(node *root) {
     if( root == NULL) 
         return 0;
 return  max( getHeight(root->left), getHeight(root->right) ) + 1;
}
node *insert(node *root, int val) {
     if( root == NULL) {
         root = new node();
         root->val  = val;
         root->left = root->right = NULL;
     } 
     else if( val < root->val ) {
              root->left = insert(root->left, val);
          if( getHeight(root->left) - getHeight(root->right) == 2)
              root = val < root->left->val ? rotateRight(root) :  rotateLeftRight(root);
     } 
	 else {
          root->right = insert(root->right, val);
          if( getHeight(root->left) - getHeight(root->right) == -2 )
              root = val > root->right->val ? rotateLeft(root) :
              rotateRightLeft(root);
    }
    return root;
}
int main() {
 int n, val;
 scanf("%d", &n);
 node *root = NULL;
 for( int i = 0; i < n; i++) {
      scanf("%d", &val);
      root = insert(root, val);
 }
 printf("%d", root->val);
 return 0;
}