Submission #625776

#	Time	Username	Problem	Language	Result	Execution time	Memory
625776		flashmt	Catfish Farm (IOI22_fish)	C++17	100 / 100	146 ms	15332 KiB

fish

#include <bits/stdc++.h>
using namespace std;
const long long oo = 1LL << 60;

long long max_weights(int n, int m, vector<int> x, vector<int> y, vector<int> w)
{
  vector<vector<pair<int, int>>> fish(n);
  for (int i = 0; i < m; i++)
    fish[x[i]].push_back({y[i], w[i]});

  vector<long long> bestPrefix(n, -oo);
  // f: left, g: right
  vector<long long> f, g, lastF, lastG;
  for (int x = 0; x < n; x++)
  {
    sort(begin(fish[x]), end(fish[x]));
    int sz = size(fish[x]);
    swap(f, lastF);
    swap(g, lastG);
    f = g = vector<long long>(sz, -oo);

    long long bestLastF = -oo, bestCurF = -oo;
    for (int i = sz - 1, j = int(size(lastF)) - 1; i >= 0; i--)
      if (x)
      {
        auto [y, w] = fish[x][i];
        f[i] = max(bestCurF, 0LL) + w;
        if (x >= 2)
          f[i] = max(f[i], bestPrefix[x - 2] + w);
        while (j >= 0 && fish[x - 1][j].first > y)
          bestLastF = max(bestLastF, lastF[j--]);
        f[i] = max(f[i], bestLastF + w);
        bestCurF = max(bestCurF, f[i]);
      }

    if (!empty(lastF))
      bestLastF = *max_element(begin(lastF), end(lastF));

    long long bestLastG = -oo, bestCurG = -oo;
    for (int i = 0, j = 0; i < sz; i++)
      if (x < n - 1)
      {
        auto [y, w] = fish[x][i];
        g[i] = max(bestCurG, 0LL) + w;
        if (x >= 2)
          g[i] = max(g[i], bestPrefix[x - 2] + w);
        g[i] = max(g[i], bestLastF + w);
        while (j < size(lastG) && fish[x - 1][j].first < y)
          bestLastG = max(bestLastG, lastG[j++]);
        g[i] = max(g[i], bestLastG + w);
        bestCurG = max(bestCurG, g[i]);
      }

    if (x)
      bestPrefix[x] = bestPrefix[x - 1];
    bestPrefix[x] = max({bestPrefix[x], bestCurF, bestCurG});
  }

  return bestPrefix[n - 1];
}

Compilation message (stderr)

fish.cpp: In function 'long long int max_weights(int, int, std::vector<int>, std::vector<int>, std::vector<int>)':
fish.cpp:48:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   48 |         while (j < size(lastG) && fish[x - 1][j].first < y)
      |                ~~^~~~~~~~~~~~~

• Subtask 1: 3 / 3
• Subtask 2: 6 / 6
• Subtask 3: 9 / 9
• Subtask 4: 14 / 14
• Subtask 5: 21 / 21
• Subtask 6: 17 / 17
• Subtask 7: 14 / 14
• Subtask 8: 16 / 16