Submission #74595

#	Time	Username	Problem	Language	Result	Execution time	Memory
74595		nobik	Skyscraper (JOI16_skyscraper)	C++14	100 / 100	295 ms	79392 KiB

skyscraper

#include <bits/stdc++.h>
using namespace std;

const int mod = 1000 * 1000 * 1000 + 7;

const int N = 105;
const int L = 1005;

int n, l, a[N], f[N][L][N][2][2];

void add(int &x, int y) {
  x += y;
  if (x >= mod) {
    x -= mod;
  }
}

int main() {
  cin >> n >> l;
  for (int i = 0; i < n; ++i) {
    cin >> a[i];
  }
  
  sort(a, a + n);
  reverse(a, a + n);
  
  for (int x = 0; x < 2; ++x)
    for (int y = 0; y < 2; ++y)
      f[0][0][1][x][y] = 1;
  
  for (int i = 1; i < n; ++i) {
    for (int j = 0; j <= l; ++j) {
      for (int w = 1; w <= i; ++w) {
        for (int x = 0; x < 2; ++x) {
          for (int y = 0; y < 2; ++y) {
            int r, nj, nw, p;
            r = f[i - 1][j][w][x][y];
            nj = j + (2 * w - x - y) * (a[i - 1] - a[i]);
            
            if (r == 0 || nj > l) {
              continue;
            }
            
            if (w == 1 && x && y) {
              continue;
            }
            
            {
              nw = w + 1;
              add(f[i][nj][nw][x][y], r);
              if (x == 0) add(f[i][nj][nw][1][y], r);
              if (y == 0) add(f[i][nj][nw][x][1], r);
            }
            
            {
              add(f[i][nj][w][x][y], 1LL * (2 * w - x - y) * r % mod);
            }
            
            {
              {
                nw = w - 1;
                p = (x ? w - x - y : 0) + (y ? w - x - y : 0) + (w - x - y) * (w - x - y - 1);
                if (nw == 1 && x && y) ++p;
                add(f[i][nj][nw][x][y], 1LL * p * r % mod);
              }
              
              if (x == 0) {
                p = w - (w > 1 && y);
                add(f[i][nj][w][1][y], 1LL * p * r % mod);
              }
              
              if (y == 0) {
                p = w - (w > 1 && x);
                add(f[i][nj][w][x][1], 1LL * p * r % mod);
              }
            }
          }
        }
      }
    }
  }
  
  int r = 0;
  for (int i = 0; i <= l; ++i)
    add(r, f[n - 1][i][1][1][1]);
    
  cout << r << '\n';
}

• Subtask 1: 5 / 5
• Subtask 2: 15 / 15
• Subtask 3: 80 / 80