Submission #1274310

#	Time	Username	Problem	Language	Result	Execution time	Memory
1274310		strange420	Triple Peaks (IOI25_triples)	C++20	0 / 100	30 ms	18708 KiB

triples

#include "triples.h"

long long count_triples(std::vector<int> H) {
  std::vector<std::vector<int>> asd (H.size());
  for (int i=0; i<H.size(); i++)
    asd[H[i]].push_back(i);

  // Compute side mappings
  long long ans = 0;
  for (int main_peak=1; main_peak<H.size(); main_peak++) {
    for (int j=0; j<asd[main_peak].size(); j++) {
      int peak_index = asd[main_peak][j];

      // check lower
      if (peak_index - main_peak >= 0) {
        int sub_peak_index = peak_index - main_peak;
        int sub_peak = H[sub_peak_index];

        // check from sub
        if (sub_peak_index - sub_peak >= 0)
          if (H[sub_peak_index - sub_peak] == sub_peak + main_peak)
            ans++;

        if (sub_peak_index + sub_peak < H.size())
          if (H[sub_peak_index + sub_peak] + sub_peak == main_peak)
            ans++;

        // check from main
        if (peak_index - sub_peak >= 0)
          if (H[peak_index - sub_peak] + sub_peak == main_peak)
            ans++;

        if (peak_index + sub_peak < H.size())
          if (H[peak_index + sub_peak] == sub_peak + main_peak)
            ans++;
      }

      // check upper
      if (peak_index + main_peak < H.size()) {
        int sub_peak_index = peak_index + main_peak;
        int sub_peak = H[sub_peak_index];

        // check from sub
        if (sub_peak_index - sub_peak >= 0)
          if (H[sub_peak_index - sub_peak] + sub_peak == main_peak)
            ans++;

        if (sub_peak_index + sub_peak < H.size())
          if (H[sub_peak_index + sub_peak] == main_peak + sub_peak)
            ans++;

        // check from main
        if (peak_index - sub_peak >= 0)
          if (H[peak_index - sub_peak] == main_peak + sub_peak)
            ans++;

        if (peak_index + sub_peak < H.size())
          if (H[peak_index + sub_peak] + sub_peak == main_peak)
            ans++;
      }
    }
  }
  ans /= 2;

  std::vector<std::vector<int>> cache(H.size());
  for (int i=0; i<H.size(); i++)
    if (i-H[i] >= 0)
      cache[i-H[i]].push_back(i);

  // Compute opposite mappings
  for (int i=0;i<H.size(); i++) {
    if (i + H[i] >= H.size()) continue;
    for (int x: cache[i+H[i]])
      if (H[H[x] + i] == H[i] + H[x])
        ans++;
  }

  return ans;
}

std::vector<int> construct_range(int M, int K) {
  return {1, 1, 1};
}

• Subtask 0: 0 / 0
• Subtask 1: 0 / 8
• Subtask 2: 0 / 6
• Subtask 3: 0 / 10
• Subtask 4: 0 / 11
• Subtask 5: 0 / 16
• Subtask 6: 0 / 19
• Subtask 7: 0 / 5
• Subtask 8: 0 / 5
• Subtask 9: 0 / 5
• Subtask 10: 0 / 5
• Subtask 11: 0 / 5
• Subtask 12: 0 / 5