Path Sum

/** * 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;        if(root->left==NULL&&root->right==NULL&&root->val==sum) return true;        return hasPathSum(root->left,sum-root->val)||hasPathSum(root->right,sum-root->val);    }};