leetcode/ValidateBinarySearchTree.java at master · gamblegear/leetcode

28 lines (23 loc) · 729 Bytes

/**

* Definition for binary tree

* public class TreeNode {

* int val;

* TreeNode left;

* TreeNode right;

* TreeNode(int x) { val = x; }

* }

public class Solution {

public boolean isValidBST(TreeNode root) {

// Start typing your Java solution below

// DO NOT write main() function

int max = Integer.MAX_VALUE;

int min = Integer.MIN_VALUE;

return isBST(root,max,min);

}

public boolean isBST(TreeNode root, int max, int min){

if(root == null) return true;

if(root.val>=max || root.val<=min) return false;

return isBST(root.left, root.val, min) && isBST(root.right, max, root.val);

}

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