112. 路径总和🔖DFS

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

/**

- Definition for a binary tree node.
- function TreeNode(val, left, right) {
-     this.val = (val===undefined ? 0 : val)
-     this.left = (left===undefined ? null : left)
-     this.right = (right===undefined ? null : right)
- }
  \*/
  /\*\*
- @param {TreeNode} root
- @param {number} targetSum
- @return {boolean}
  \*/
  var hasPathSum = function(root, targetSum) {
  let result = false
  let dfs = (data, presum, tar) => {
  if (data) {
  presum = data.val + presum
  if (!data.left && !data.right) {
  if (presum == tar) {
  result = true
  }
  }
  dfs(data.left, presum, tar)
  dfs(data.right, presum, tar)
  }
  }
  dfs(root, 0, targetSum)
  return result
  };