nikunjsoni

145

Mar 25th, 2021
63
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  1. /**
  2.  * Definition for a binary tree node.
  3.  * struct TreeNode {
  4.  *     int val;
  5.  *     TreeNode *left;
  6.  *     TreeNode *right;
  7.  *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
  8.  *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
  9.  *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
  10.  * };
  11.  */
  12. class Solution {
  13. public:
  14.     vector<int> postorderTraversal(TreeNode* root) {
  15.         vector<int> ans;
  16.         stack<TreeNode*> s;
  17.        
  18.         if(root) s.push(root);
  19.         while(!s.empty()){
  20.             TreeNode *tmp = s.top();
  21.             s.pop();
  22.             ans.push_back(tmp->val);
  23.             if(tmp->left) s.push(tmp->left);
  24.             if(tmp->right) s.push(tmp->right);
  25.         }
  26.         reverse(ans.begin(), ans.end());
  27.         return ans;
  28.     }
  29. };
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