binary-tree-postorder-traversal

Given a binary tree, return the postorder traversal of its nodes’ values.
For example:
Given binary tree{1,#,2,3},
1
\
2
/
3

return[3,2,1].
Note: Recursive solution is trivial, could you do it iteratively?

/*
前序遍历  根->右->左 结果再reverse一下
 */
class Solution {
public:
    vector<int> temp;
    vector<int> postorderTraversal(TreeNode *root) {

         postorder(root);
        reverse(temp.begin(),temp.end());
        return temp;

    }
     void postorder(TreeNode *root) 
     {
         if(!root)
         {
             return;
         }
         temp.push_back(root->val);
          postorder(root->right);
          postorder(root->left);

     }
};

class Solution {
public:
    vector<int> temp;
    vector<int> postorderTraversal(TreeNode *root) {

         postorder(root);
        return temp;

    }
     void postorder(TreeNode *root) 
     {
         if(!root)
         {
             return;
         }
          postorder(root->left);
         postorder(root->right);
         temp.push_back(root->val);

     }
};