首发于 语雀@blueju

    https://leetcode-cn.com/problems/path-sum/

    1. /**
    2.  * Definition for a binary tree node.
    3.  * function TreeNode(val, left, right) {
    4.  *     this.val = (val===undefined ? 0 : val)
    5.  *     this.left = (left===undefined ? null : left)
    6.  *     this.right = (right===undefined ? null : right)
    7.  * }
    8.  */
    9. /**
    10.  * @param {TreeNode} root
    11.  * @param {number} targetSum
    12.  * @return {boolean}
    13.  */
    14. var hasPathSum = function (root, targetSum) {
    15.     function traverse(root) {
    16.         if (root === null) {
    17.             return
    18.         }
    19.         trace.push(root.val)
    20.         if (root.left === null && root.right === null) {
    21.             let total = trace.reduce((prev, curr) => prev + curr, 0)
    22.             if (total === targetSum) {
    23.                 found = true
    24.             }
    25.             trace.pop()
    26.             return
    27.         }
    28.         traverse(root.left)
    29.         traverse(root.right)
    30.         trace.pop()
    31.     }
    32.     let found = false
    33.     let trace = []
    34.     traverse(root)
    35.     return found
    36. };