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;
};