题目

思路

AVL树插入算法，输出根即可

代码

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

	for (int i = 0; i < n; i++) {
		scanf_s("%d", &val);
		insert(root, val);
	}
	printf("%d", root->val);
	return 0;
}