LeetCode:Binary Tree Postorder Traversal

 1 /**
 2  * Definition for a binary tree node.
 3  * struct TreeNode {
 4  *     int val;
 5  *     TreeNode *left;
 6  *     TreeNode *right;
 7  *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 8  * };
 9  */
10 class Solution {
11 public:
12     vector<int> postorderTraversal(TreeNode* root) {
13         vector<int> result;
14         postorder(root,result);
15         return result;
16         
17         
18     }
19     
20     void postorder(TreeNode *node,vector<int> &result)
21     {
22         if(node!=NULL)
23         {
24             postorder(node->left,result);
25             postorder(node->right,result);
26             result.push_back(node->val);
27         }
28         
29     }
30 };