[刷题] 112 Path Sum

 1 class Solution {
 2 public:
 3     bool hasPathSum(TreeNode* root, int sum) {
 4         
 5         if( root == NULL )
 6             return false;
 7         
 8         if( root->left == NULL && root->right == NULL )
 9             return root->val == sum;
10         
11         if( hasPathSum( root->left , sum - root->val ) )
12             return true;
13         
14         if( hasPathSum( root->right , sum - root->val ) )
15             return true;
16             
17         return false;
18     }
19 };