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);
}
};