_700.java

package com.fishercoder.solutions;

import com.fishercoder.common.classes.TreeNode;

/**
 * 700. Search in a Binary Search Tree
 *
 * Given the root node of a binary search tree (BST) and a value.
 * You need to find the node in the BST that the node's value equals the given value.
 * Return the subtree rooted with that node. If such node doesn't exist, you should return NULL.
 *
 * For example,
 *
 * Given the tree:
 *         4
 *        / \
 *       2   7
 *      / \
 *     1   3
 *
 * And the value to search: 2
 * You should return this subtree:
 *
 *       2
 *      / \
 *     1   3
 * In the example above, if we want to search the value 5, since there is no node with value 5, we should return NULL.
 *
 * Note that an empty tree is represented by NULL,
 * therefore you would see the expected output (serialized tree format) as [], not null.
 * */
public class _700 {
    public static class Solution1 {
        public TreeNode searchBST(TreeNode root, int val) {
            if (root == null) {
                return null;
            } else if (root.val == val) {
                return root;
            } else if (root.val > val) {
                return searchBST(root.left, val);
            } else {
                return searchBST(root.right, val);
            }
        }
    }
}