700.SearchBST.cs

// 700. Search in a Binary Search Tree

// You are given the root of a binary search tree (BST) and an integer val.

// Find the node in the BST that the node's value equals val and return the subtree rooted with that node. If such a node does not exist, return null.

 

// Example 1:


// Input: root = [4,2,7,1,3], val = 2
// Output: [2,1,3]
// Example 2:


// Input: root = [4,2,7,1,3], val = 5
// Output: []
/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     public int val;
 *     public TreeNode left;
 *     public TreeNode right;
 *     public TreeNode(int val=0, TreeNode left=null, TreeNode right=null) {
 *         this.val = val;
 *         this.left = left;
 *         this.right = right;
 *     }
 * }
 */
public class Solution {
    public TreeNode SearchBST(TreeNode root, int val) {
        if(root == null)
            return root;
        if(root.val == val)
            return root;
        if(root.val > val)
            return SearchBST(root.left,val);
        return SearchBST(root.right,val);
    }
}