Leetcode -- Path Sum

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