Submission #1251462

#	Time	Username	Problem	Language	Result	Execution time	Memory
1251462		flashmt	Triple Peaks (IOI25_triples)	C++20	51 / 100	2095 ms	43076 KiB

triples

#include "triples.h"
#include <bits/stdc++.h>
#ifdef LOCAL
#include "Debug.h"
#else
#define debug(...) 42
#endif
using namespace std;

long long calc(vector<int> h)
{
  int n = size(h);
  vector<int> l(n), r(n);
  vector<vector<int>> lAt(n * 3), rAt(n * 3);
  for (int i = 0; i < n; i++)
  {
    l[i] = i - h[i];
    lAt[l[i] + n].push_back(h[i]);
    r[i] = i + h[i];
    rAt[r[i] + n].push_back(h[i]);
  }

  for (int i = 0; i < n * 3; i++)
  {
    sort(begin(lAt[i]), end(lAt[i]));
    sort(begin(rAt[i]), end(rAt[i]));
  }

  long long res = 0;
  for (int i = 0; i < n; i++)
  {
    int j = r[i];
    if (j < n)
    {
      // 2.3..5
      res += r[j] < n && h[r[j]] == h[i] + h[j];

      // 2.5..3
      if (h[j] > h[i])
      {
        int k = j + h[j] - h[i];
        if (k < n && l[k] == j)
          res++;
      }

      // 5.3..2
      if (h[j] < h[i])
      {
        int k = i + h[j];
        if (r[k] == j && h[k] != h[j]) // exclude 211
          res++;
      }
    }

    // k.2..5.3..j
    int ll = l[i] + n, rr = r[i] + n, szL = size(lAt[ll]), szR = size(rAt[rr]);
    for (int u = 0, v = szR - 1; u < szL && v >= 0;)
      if (lAt[ll][u] + rAt[rr][v] == h[i])
      {
        res += lAt[ll][u] != rAt[rr][v];
        u++;
      }
      else if (lAt[ll][u] + rAt[rr][v] < h[i]) u++;
      else v--;
  }

  for (int i = 0; i < n; i++)
  {
    int j = l[i];
    if (j < 0)
      continue;

    // 5.2..3
    if (l[j] >= 0 && h[l[j]] == h[i] + h[j])
      res++;

    // 3.2..5
    int k = i + h[j];
    if (r[j] != i && k < n && h[k] == h[i] + h[j]) // exclude 112
      res++;
  }

  return res;
}

long long count_triples(vector<int> h) {
  return calc(h);
}

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

• Subtask 0: 0 / 0
• Subtask 1: 8 / 8
• Subtask 2: 6 / 6
• Subtask 3: 10 / 10
• Subtask 4: 11 / 11
• Subtask 5: 16 / 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