# Description

Given a binary tree and a sum, determine if the tree has a root-to-leaf path such that adding up all the values along the path equals the given sum.

For example:
Given the below binary tree and sum = 22,
5
/
4 8
/ /
11 13 4
/ \
7 2 1
return true, as there exist a root-to-leaf path 5->4->11->2 which sum is 22.

The original problem is here.

The original code is here.

# My Solution

I solve this problem in C++, as below:

``````/*
* Path Sum
*Author: shuaijiang
*Email: zhaoshuaijiang8@gmail.com
*/
#include<iostream>
#include<math.h>
#include<stdlib.h>
using namespace std;

/**
* Definition for a binary tree node.
* 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 == NULL)
return false;
return     sumNum(root,0,sum);
}
bool sumNum(TreeNode * root, int val,int sum){
if(root == NULL)
return false;
val = val + root->val;
if(root->left == NULL && root->right == NULL){
if(val == sum)
return true;
else
return false;
}
return (sumNum(root->left,val,sum) || sumNum(root->right,val,sum));
}
};
``````

# Note

In the solution, recursion is needed. During these steps, we need compute the sum of all the values in the path.