/*
 * @lc app=leetcode.cn id=98 lang=javascript
 *
 * [98] 验证二叉搜索树
 */

// @lc code=start
/**
 * Definition for a binary tree node.
 * function TreeNode(val, left, right) {
 *     this.val = (val===undefined ? 0 : val)
 *     this.left = (left===undefined ? null : left)
 *     this.right = (right===undefined ? null : right)
 * }
 */
/**
 * @param {TreeNode} root
 * @return {boolean}
 */
 let verifyBST = (root,min,max) =>{
    if(!root) return true;
    if(root.val>=max || root.val<=min) return false;
    return verifyBST(root.left,min,root.val) && verifyBST(root.right,root.val,max)
}
var isValidBST = function(root) {
   return verifyBST(root,-2e32,2e32)
};
// @lc code=end