leetcode---Path Sum

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.

/** * 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 dfs(TreeNode *root, int sum, int cur)    {        if(root == NULL)            return false;        if(root->left == NULL && root->right == NULL)            return cur + root->val == sum;        return dfs(root->left, sum, cur+root->val) || dfs(root->right, sum, cur+root->val);    }    bool hasPathSum(TreeNode* root, int sum)     {        if(root == NULL)            return false;        return dfs(root, sum, 0);    }};