#285 - Inorder Successor in BST

Medium • View on LeetCode • View on GitHub

Depth-First Search Tree Binary Tree Binary Search Tree

Problem Description

Given the root of a binary search tree and a node p in it, return the in-order successor of that node in the BST. If the given node has no in-order successor in the tree, return null.

The successor of a node p is the node with the smallest key greater than p.val.

Solution

/**
 * Definition for a binary tree node.
 * function TreeNode(val) {
 *     this.val = val;
 *     this.left = this.right = null;
 * }
 */
/**
 * @param {TreeNode} root
 * @param {TreeNode} p
 * @return {TreeNode}
 */
var inorderSuccessor = function(root, p) {
  let successor = null;
  while (root) {
    if (p.val < root.val) {
      successor = root;
      root = root.left;
    } else {
      root = root.right;
    }
  }
  return successor;
};