Submission #1017066

#	Time	Username	Problem	Language	Result	Execution time	Memory
1017066		MilosMilutinovic	Soccer Stadium (IOI23_soccer)	C++17	1.50 / 100	1626 ms	657692 KiB

soccer

#include "soccer.h"
#include <bits/stdc++.h>
 
using namespace std;
 
const int MAX = 2005;
const int LOG = 12;
 
int n, a[MAX][MAX];
int L[MAX][MAX];
int R[MAX][MAX];
int U[MAX][MAX];
int D[MAX][MAX];
int go[MAX][MAX];
int logs[MAX];
int st_U[MAX][MAX][LOG];
int st_D[MAX][MAX][LOG];
int res;
map<array<int, 4>, bool> was;
 
int query_U(int i, int l, int r) {
  int k = logs[r - l + 1];
  return max(st_U[i][l][k], st_U[i][r - (1 << k) + 1][k]);
}
 
int query_D(int i, int l, int r) {
  int k = logs[r - l + 1];
  return min(st_D[i][l][k], st_D[i][r - (1 << k) + 1][k]);
}
 
void rec(int xl, int xr, int yl, int yr, int side, int cur) {
  if (was[{xl, xr, yl, yr}]) {
    return;
  }
  res = max(res, cur);
  was[{xl, xr, yl, yr}] = true;
  if (xl > 0) {
    // up
    int ptr = yl;
    while (ptr <= yr) {
      if (a[xl - 1][ptr] == 1) {
        ptr = go[xl - 1][ptr];
        continue;
      }
      int t = min(yr, R[xl - 1][ptr]);
      int new_x = query_U(xl - 1, ptr, t);
      rec(xl - 1, xr, ptr, t, 1, cur + t - ptr + 1);
      ptr = R[xl - 1][ptr] + 1;
    }
  }
  if (xr + 1 < n) {
    // down
    int ptr = yl;
    while (ptr <= yr) {
      if (a[xr + 1][ptr] == 1) {
        ptr = go[xr + 1][ptr];
        continue;
      }
      int t = min(yr, R[xr + 1][ptr]);
      int new_x = query_D(xr + 1, ptr, t);
      rec(xl, xr + 1, ptr, t, 0, cur + t - ptr + 1);
      ptr = R[xr + 1][ptr] + 1;
    }
  }
}
 
int biggest_stadium(int N, vector<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 = 0; i < n; i++) {
    for (int j = 0; j < n; j++) {
      if (a[i][j] == 1) {
        continue;
      }
      int p = j;
      while (p + 1 < n && a[i][p + 1] == 0) {
        p += 1;
      }
      for (int k = j; k <= p; k++) {
        L[i][k] = j;
        R[i][k] = p;
      }
      j = p;
    }
  }
  for (int j = 0; j < n; j++) {
    for (int i = 0; i < n; i++) {
      if (a[i][j] == 1) {
        continue;
      }
      int p = i;
      while (p + 1 < n && a[p + 1][j] == 0) {
        p += 1;
      }
      for (int k = i; k <= p; k++) {
        U[k][j] = i;
        D[k][j] = p;
      }
      i = p;
    }
  }
  for (int i = 2; i <= n; i++) {
    logs[i] = logs[i >> 1] + 1;
  }
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < n; j++) {
      st_U[i][j][0] = U[i][j];
      st_D[i][j][0] = D[i][j];
    }
  }
  for (int k = 1; k < LOG; k++) {
    for (int i = 0; i < n; i++) {
      for (int j = 0; j + (1 << k) <= n; j++) {
        st_U[i][j][k] = max(st_U[i][j][k - 1], st_U[i][j + (1 << (k - 1))][k - 1]);
        st_D[i][j][k] = min(st_D[i][j][k - 1], st_D[i][j + (1 << (k - 1))][k - 1]);
      }
    }
  }
  for (int i = 0; i < n; i++) {
    for (int j = n - 1; j >= 0; j--) {
      if (a[i][j] == 1) {
        go[i][j] = (j == n - 1 ? n : go[i][j + 1]);
      } else {
        go[i][j] = j;
      }
    }
  }
  res = 0;
  vector<array<int, 4>> s;
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < n; j++) {
      if (a[i][j] == 1) {
        continue;
      }
      if (j == 0 || a[i][j - 1] == 1) {
        s.push_back({R[i][j] - j + 1, i, j, R[i][j]});
      }
    }
  }
  sort(s.rbegin(), s.rend());
  for (auto& p : s) {
    int i = p[1];
    int l = p[2], r = p[3];
    rec(i, i, l, r, -1, r - l + 1);
  }
  return res;
}

Compilation message (stderr)

soccer.cpp: In function 'void rec(int, int, int, int, int, int)':
soccer.cpp:46:11: warning: unused variable 'new_x' [-Wunused-variable]
   46 |       int new_x = query_U(xl - 1, ptr, t);
      |           ^~~~~
soccer.cpp:60:11: warning: unused variable 'new_x' [-Wunused-variable]
   60 |       int new_x = query_D(xr + 1, ptr, t);
      |           ^~~~~

• Subtask 0: 0 / 0
• Subtask 1: 1.5 / 6
• Subtask 2: 0 / 8
• Subtask 3: 0 / 22
• Subtask 4: 0 / 18
• Subtask 5: 0 / 16
• Subtask 6: 0 / 30