[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.

class Solution {
public:
    bool hasPathSum(TreeNode *root, int sum) {
		// Start typing your C/C++ solution below
		// DO NOT write int main() function
		if(root==NULL)
			return false;
        if(!root->left && !root->right && root->val==sum)
            return true;
		return root->left && hasPathSum(root->left,sum-root->val)|| root->right && hasPathSum(root->right,sum-root->val);

	}
};