Submission #1155766

#	Time	Username	Problem	Language	Result	Execution time	Memory
1155766		fryingduc	Skyscraper (JOI16_skyscraper)	C++20	0 / 100	1 ms	580 KiB

skyscraper

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

#ifdef duc_debug
#include "bits/debug.h"
#else
#define debug(...)
#endif

const int maxn = 105;
const int L = 1005;
const int mod = 1e9 + 7;
int n, l, a[maxn];
int f[maxn][maxn][L][3];

int add(int x, int y) {
  if (y < 0) y += mod;
  x = x + y;
  if (x >= mod) x -= mod;
  return x;
}

void solve() {
  cin >> n >> l;
  for (int i = 1; i <= n; ++i) {
    cin >> a[i];
  }
  if (n == 1) {
    cout << 1;
    return;
  }
  sort(a + 1, a + n + 1);
  f[0][0][0][0] = 1;
  a[n + 1] = 1e5;
  for (int i = 1; i <= n; ++i) {
    for (int j = 1; j <= i; ++j) {
      for (int m = 0; m < 3; ++m) {
        int dt = (2 * j - m) * (a[i + 1] - a[i]);
        if (i + j + m - 1 > n) continue;
        for (int k = dt; k <= l; ++k) {
          int &cur = f[i][j][k][m];
          // make new cc without endpoint
          cur = add(cur, f[i - 1][j - 1][k - dt][m]);
          // make new cc with an endpoint
          if (m) {
            cur = add(cur, 1ll * (3 - m) * f[i - 1][j - 1][k - dt][m - 1] % mod);
          }
          // append to an existing component without endpoint
          cur = add(cur, 1ll * (2 * j - m) * f[i - 1][j][k - dt][m] % mod);
          // append to an exsting component with endpoint
          if (m) {
            if (m == 1) {
              cur = add(cur, 2ll * j * f[i - 1][j][k - dt][m - 1] % mod);
            } else {
              if (j == 1) {
                if (i == n) {
                  cur = add(cur, f[i - 1][j][k - dt][m - 1]);
                }
              } else {
                cur = add(cur, 1ll * (j - 1) * f[i - 1][j][k - dt][m - 1] % mod);
              }
            }
          }
          // join 2 components
          if (m == 2 and i == n) {
            cur = add(cur, f[i - 1][j + 1][k - dt][m]);
          } else {
            cur = add(cur, 1ll * j * (j + 1 - m) * f[i - 1][j + 1][k - dt][m] % mod);
          }
        }
      }
    }
  }
  int res = 0;
  for (int i = 0; i <= l; ++i) {
    res = add(res, f[n][1][i][2]);
  }
  cout << res;
}

signed main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);

  solve();

  return 0;
}

• Subtask 1: 0 / 5
• Subtask 2: 0 / 15
• Subtask 3: 0 / 80