#include<iostream>

#include<vector>

#include<stack>

using namespace std;

struct TreeNode {

int val;

TreeNode *left;

TreeNode *right;

TreeNode(int x) : val(x), left(NULL), right(NULL) {}

};

class Solution {

public:

vector<int> postorderTraversal(TreeNode *root) {

vector<int> path;

if(root==NULL)return path;

stack<TreeNode*> stk;

stk.push(root);

TreeNode* cur = NULL;

while(!stk.empty()) {

cur = stk.top();

if(cur->left ==NULL && cur->right ==NULL) {

path.push_back(cur->val);

stk.pop();

} else {

if(cur->right) {

stk.push(cur->right);

cur->right = NULL;

}

if(cur->left) {

stk.push(cur->left);

cur->left = NULL;

}

}

}

return path;

}

};

int main() {

}