leetcode

Solution to some Leetcode problems written in C++
git clone git://git.dimitrijedobrota.com/leetcode.git
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0145.cpp (760B)

      1 class Solution {
      2   public:
      3     vector<int> postorderTraversal(TreeNode *root) {
      4         if (!root) return {};
      5 
      6         vector<int> res;
      7         unordered_set<TreeNode *> s;
      8         stack<TreeNode *> st;
      9 
     10         while (root) {
     11             st.push(root);
     12             root = root->left;
     13         }
     14 
     15         while (!st.empty()) {
     16             TreeNode *root = st.top();
     17             st.pop();
     18             if (!s.count(root)) {
     19                 s.insert(root);
     20                 st.push(root);
     21                 root = root->right;
     22                 while (root) {
     23                     st.push(root);
     24                     root = root->left;
     25                 }
     26             } else {
     27                 res.push_back(root->val);
     28             }
     29         }
     30 
     31         return res;
     32     }
     33 };