Submission #964435

#	Time	Username	Problem	Language	Result	Execution time	Memory
964435		nguyentunglam	Soccer Stadium (IOI23_soccer)	C++17	100 / 100	2069 ms	415888 KiB

soccer

#include "soccer.h"
#include<bits/stdc++.h>
#define all(v) v.begin(), v.end()
using namespace std;

const int N = 2010;

int n;

bool a[N][N];

namespace AC {
const int N = 2010, M = 2e3 * 2e3 * 2 + 10;

int b[N], L[N], R[N], dp[M], trans[2][M];

int close[N];

vector<int> open[N], lst[N], event[2][N];

tuple<int, int, int, int> rect[M];

int solve() {
  int m = 0;

  auto histogram = [&] () {
    stack<int> st;
    for(int i = 1; i <= n; i++) {
      while (!st.empty() && b[st.top()] >= b[i]) st.pop();
      L[i] = st.empty() ? 0 : st.top();
      st.push(i);
    }
    while (!st.empty()) st.pop();
    for(int i = n; i >= 1; i--) {
      while (!st.empty() && b[st.top()] >= b[i]) st.pop();
      R[i] = st.empty() ? n + 1 : st.top();
      st.push(i);
    }
  };

  for(int i = 1; i <= n; i++) {
    for(int j = 1; j <= n; j++) {
      if (a[i][j]) b[j] = 0;
      else b[j]++;
    }
    histogram();
    for(int j = 1; j <= n; j++) if (b[j]) {
      rect[++m] = make_tuple(i - b[j] + 1, i, L[j] + 1, R[j] - 1);
    }
  }

  for(int j = 1; j <= n; j++) b[j] = 0;

  for(int i = n; i >= 1; i--) {
    for(int j = 1; j <= n; j++) {
      if (a[i][j]) b[j] = 0;
      else b[j]++;
    }
    histogram();
    for(int j = 1; j <= n; j++) if (b[j]) {
      rect[++m] = make_tuple(i, i + b[j] - 1, L[j] + 1, R[j] - 1);
    }
  }


  for(int i = 1; i <= m; i++) {
    lst[get<1> (rect[i]) - get<0> (rect[i])].push_back(i);
  }

  for(int delta = 0; delta < n; delta++) {
    for(int &i : lst[delta]) {
      int x1, x2, y1, y2; tie(x1, x2, y1, y2) = rect[i];
      event[0][x2].emplace_back(i);
      event[1][x1].emplace_back(i);
    }
  }

  for(int i = 1; i <= n; i++) for(int t = 0; t < 2; t++) {
    for(auto &j : event[t][i]) {
      int x1, x2, y1, y2; tie(x1, x2, y1, y2) = rect[j];
      open[y1].push_back(j);
      close[y2]++;
    }

    stack<int> st;

    for(int j = 1; j <= n; j++) {
      for(auto &k : open[j]) {
        trans[t][k] = st.empty() ? 0 : st.top();
        st.push(k);
      } open[j].clear();
      while (close[j]--) st.pop();
      close[j] = 0;
    }
  }

  int ans = 0;

  for(int delta = 0; delta < n; delta++) {
    for(int &i : lst[delta]) {
      int x1, x2, y1, y2; tie(x1, x2, y1, y2) = rect[i];
      dp[i] = (x2 - x1 + 1) * (y2 - y1 + 1);
      if (trans[0][i]) { // top
        int j = trans[0][i];
        dp[i] = max(dp[i], dp[j] + (get<0> (rect[j]) - x1) * (y2 - y1 + 1));
      } // bottom
      if (trans[1][i]) {
        int j = trans[1][i];
        dp[i] = max(dp[i], dp[j] + (x2 - get<1> (rect[j])) * (y2 - y1 + 1));
      }
      ans = max(ans, dp[i]);
    }
  }

  cerr << 1.0 * clock() / CLOCKS_PER_SEC << endl;

  return ans;
}
}


int biggest_stadium(int N, std::vector<std::vector<int>> F)
{
  n = N;
  for(int i = 0; i < n; i++) for(int j = 0; j < n; j++) a[i][j] = F[i][j];
  for(int i = 1; i <= n; i++) for(int j = 1; j <= n; j++) a[i][j] = F[i - 1][j - 1];
  return AC::solve();
}

#ifdef ngu
int main()
{
  freopen ("task.inp", "r", stdin);
  freopen ("task.out", "w", stdout);
    int N;
    assert(1 == scanf("%d", &N));
    std::vector<std::vector<int>> F(N, std::vector<int>(N));
    for (int i = 0; i < N; i++)
    {
        for (int j = 0; j < N; j++)
        {
            assert(1 == scanf("%d", &F[i][j]));
        }
    }
    fclose(stdin);

    int res = biggest_stadium(N, F);

    printf("%d\n", res);
    fclose(stdout);
    return 0;
}
#endif // ngu

• Subtask 0: 0 / 0
• Subtask 1: 6 / 6
• Subtask 2: 8 / 8
• Subtask 3: 22 / 22
• Subtask 4: 18 / 18
• Subtask 5: 16 / 16
• Subtask 6: 30 / 30