112 Path Sum.js

// Leetcode #112 
// Language: Javascript
// Problem: https://leetcode.com/problems/path-sum/
// Author: Chihung Yu
/**
 * Definition for a binary tree node.
 * function TreeNode(val) {
 *     this.val = val;
 *     this.left = this.right = null;
 * }
 */
/**
 * @param {TreeNode} root
 * @param {number} sum
 * @return {boolean}
 */
var hasPathSum = function(root, sum) {
    if(root === null){
        return false;
    }
    
    if(root.val === sum && root.left === null && root.right === null){
        return true;
    }
    
    return hasPathSum(root.left, sum - root.val) || hasPathSum(root.right, sum - root.val);
};

/**
 * Definition for a binary tree node.
 * function TreeNode(val) {
 *     this.val = val;
 *     this.left = this.right = null;
 * }
 */
/**
 * @param {TreeNode} root
 * @param {number} sum
 * @return {boolean}
 */
var hasPathSum = function(root, sum) {
    if (root === null) {
        return false;
    }
    
    var left = root.left;
    var right = root.right;
    
    if (left === null && right === null) {
        return root.val === sum;
    }
    
    return hasPathSum(left, sum - root.val) || hasPathSum(right, sum - root.val);
};