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  1. #include<bits/stdc++.h>
  2. using namespace std;
  3.  
  4. vector<char> first_unique(vector<char> stream){
  5.     unordered_map<char, int> count;
  6.     queue<char> q;
  7.     vector<char> result;
  8.     for(char c: stream){
  9.         count[c]++;
  10.         q.push(c);
  11.         while(!q.empty() && count[q.front()] > 1){
  12.             q.pop();
  13.         }
  14.         if(!q.empty()){
  15.             result.push_back(q.front());
  16.         }
  17.         else result.push_back('#');
  18.     }
  19.     return result;
  20. }
  21.  
  22. int main(){
  23.     vector<char> input = {'a', 'b', 'c', 'd', 'e'};
  24.     vector<char> ans = first_unique(input);
  25.  
  26.     for (char ch : ans) {
  27.         cout << ch << " ";
  28.     }
  29.  
  30.     return 0;
  31.  
  32. }
Success #stdin #stdout 0.01s 5288KB
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Standard input is empty
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a a a a a
https://ideone.com/ohPcO1
language:
C++14 (gcc 8.3)
created:
2 days ago
visibility:
public

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