//leetcode submit region begin(Prohibit modification and deletion)
/**
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode() {}
* TreeNode(int val) { this.val = val; }
* TreeNode(int val, TreeNode left, TreeNode right) {
* this.val = val;
* this.left = left;
* this.right = right;
* }
* }
*/
思路:搜索树,左子树小于根节点,右子树大于根节点,根据这个特性去做
class Solution {
public boolean isValidBST(TreeNode root) {
return isValid(root,null,null);
}
boolean isValid(TreeNode root,TreeNode min,TreeNode max){
if(root==null){
return true ;
}
//节点的左子树只包含 小于 当前节点的数。
if(min!=null && min.val>=root.val){
return false;
}
//节点的右子树只包含 大于 当前节点的数。
if(max!=null && max.val<=root.val){
return false;
}
return isValid(root.left,min,root)&&isValid(root.right,root,max);
}
}
//leetcode submit region end(Prohibit modification and deletion)
标签:leetcode98,right,TreeNode,val,二叉,搜索,null,root,节点
From: https://www.cnblogs.com/xiaoshahai/p/17465566.html