ValidateBinarySearchTree.cs

// Source : https://leetcode.com/problems/validate-binary-search-tree 
// Author : codeyu 
// Date : Thursday, March 9, 2017 11:30:20 PM 

/**********************************************************************************
*
* 
* Given a binary tree, determine if it is a valid binary search tree (BST).
* 
* 
* 
* Assume a BST is defined as follows:
* 
* The left subtree of a node contains only nodes with keys less than the node's key.
* The right subtree of a node contains only nodes with keys greater than the node's key.
* Both the left and right subtrees must also be binary search trees.
* 
* 
* 
* Example 1:
* 
*     2
*    / \
*   1   3
* 
* Binary tree [2,1,3], return true.
* 
* 
* Example 2:
* 
*     1
*    / \
*   2   3
* 
* Binary tree [1,2,3], return false.
* 
*
**********************************************************************************/

using System;
using System.Collections.Generic;
using Algorithms.Utils;
namespace Algorithms
{
/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     public int val;
 *     public TreeNode left;
 *     public TreeNode right;
 *     public TreeNode(int x) { val = x; }
 * }
 */
public class Solution098 {
    public static bool IsValidBST(TreeNode root) {
        throw new NotImplementedException("TODO");
    }
}}