/**
* Definition for binary tree
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode(int x) : val(x), left(NULL), right(NULL) {}
* };
*/
vector<int> res;
void getPost(TreeNode *root) {
if(!root) return;
getPost(root->left);
getPost(root->right);
res.push_back(root->val);
}
vector<int> Solution::postorderTraversal(TreeNode* A) {
res.clear();
getPost(A);
return res;
}