path-sum leetcode C++

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 andsum = 22, 5 / 

4 8 / / 

11 13 4 / \ 

7 2 1 return true, as there exist a root-to-leaf path5->4->11->2which sum is 22.

C++

/**
 * 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 hasPathSum2(TreeNode *root, int sum) {
        if(NULL == root) return false;
        if(NULL == root->left && NULL == root->right && sum == root->val) return true;
        if(NULL != root->left && hasPathSum(root->left,sum-root->val)) return true;
        if(NULL != root->right && hasPathSum(root->right,sum-root->val)) return true;
        return false;
    }

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