Leetcoede 112 Path Sum 二叉树

二叉树的从叶子到根的和是否存在

 /**
  * Definition for binary tree
  * struct TreeNode {
  *     int val;
  *     TreeNode *left;
  *     TreeNode *right;
  *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
  * };
  */
 class Solution {
 public:

 bool hasPathSum(TreeNode *root, int sum) {
     if (!root)
     {
         return false;
     }
     if (!root->left && !root->right)
     {
         return sum == root->val;
     }
     return hasPathSum(root->left,sum - root->val)||hasPathSum(root->right,sum - root->val);
 }