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  1. #include <iostream>
  2. #include <fstream>
  3. #include <vector>
  4. #include <algorithm>
  5.  
  6. struct Line
  7. {
  8.     int start{};
  9.     int end{};
  10.     int weight{};
  11. };
  12.  
  13. enum operation {TAKE, DROP};
  14.  
  15. int optimize(operation op, std::vector<Line>::iterator it, std::vector<Line>::iterator end)
  16. {
  17.     int weight{op == TAKE ? it->weight : 0};
  18.     int line_end{it->end};
  19.  
  20.     if (op == DROP) ++it;
  21.     else while ( ++it != end)
  22.             if (it->start > line_end) break;
  23.  
  24.     if (it == end) return weight;
  25.  
  26.     return weight + std::max(optimize(TAKE, it, end),
  27.                              optimize(DROP, it, end));
  28. }
  29.  
  30. static const int size = 100;
  31.  
  32. int main()
  33. {
  34.     std::ifstream fin{"input.txt"};
  35.  
  36.     int N;
  37.     fin >> N;
  38.  
  39.     std::vector<Line> lines(size);
  40.  
  41.     for (int i{}; i < N; i++)
  42.     {
  43.         int num;
  44.         fin >> num;
  45.         Line& line = lines[num - 1];
  46.  
  47.         if (line.start == 0)
  48.             line.start = i;
  49.         line.end = i;
  50.         line.weight++;
  51.     }
  52.  
  53.     fin.close();
  54.  
  55.     std::sort(lines.begin(), lines.end(), [](const Line& a, const Line& b) {
  56.         return b.start > a.start;   
  57.     });
  58.  
  59.     int result{std::max(optimize(TAKE, lines.begin(), lines.end()),
  60.                         optimize(DROP, lines.begin(), lines.end()))
  61.               };
  62.  
  63.     std::ofstream fout{"output.txt"};
  64.     fout << result;
  65.     fout.close();
  66.  
  67.     return 0;
  68. }
Success #stdin #stdout 0s 3456KB
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https://ideone.com/dnXRkk
language:
C++14 (gcc 8.3)
created:
8 years ago
visibility:
public

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