Submission #1192575

#	Time	Username	Problem	Language	Result	Execution time	Memory
1192575		aykhn	Skyscraper (JOI16_skyscraper)	C++20	100 / 100	79 ms	13128 KiB

skyscraper

#include <bits/stdc++.h>

using namespace std;

#define int long long
#define inf 0x3F3F3F3F3F3F3F3F

const int MXN = 1e3 + 5;
const int mod = 1e9 + 7;

int dp[MXN][MXN][3], ndp[MXN][MXN][3];

void _()
{
  int n, L;
  cin >> n >> L;
  int arr[n];
  for (int &i : arr) cin >> i;
  sort(arr, arr + n);
  dp[0][1][0] = 1;
  dp[0][1][1] = 2;
  dp[0][1][2] = 1;
  int prv = 0;
  for (int &i : arr)
  {
    int val = i - prv;
    if (!prv) {prv = i; continue;}
    prv = i;
    for (int sum = 0; sum <= L; sum++) for (int c = 0; c <= n; c++) for (int f = 0; f < 3; f++)
    {
      if (!dp[sum][c][f]) continue;
      if (c < f) continue;
      int all = 2 * c - f;
      int nw = sum + val * all;
      if (nw > L) continue;
      int X = dp[sum][c][f];
      if (f < 2)
      {
        ndp[nw][c][f + 1] += X * (2 - f) % mod, ndp[nw][c][f + 1] %= mod;
        if (c + 1 <= n) ndp[nw][c + 1][f + 1] += X * (2 - f) % mod, ndp[nw][c + 1][f + 1] %= mod;
      }
      ndp[nw][c][f] += X * (2 * c - f) % mod, ndp[nw][c][f] %= mod;
      if (c + 1 <= n) ndp[nw][c + 1][f] += X * (c + 1 - f) % mod, ndp[nw][c + 1][f] %= mod;
      if (c >= 2) ndp[nw][c - 1][f] += X * (c - 1) % mod, ndp[nw][c - 1][f] %= mod;
    }
    for (int sum = 0; sum <= L; sum++) for (int c = 0; c <= n; c++) for (int f = 0; f < 3; f++) 
    {
      dp[sum][c][f] = ndp[sum][c][f];
      ndp[sum][c][f] = 0;
    }
  }
  int res = 0;
  for (int i = 0; i <= L; i++)
  {
    res += dp[i][1][2];
    res %= mod;
  }
  cout << res << '\n';
}
signed main()
{
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  int t = 1;
  // cin >> t;
  while (t--) _();
}

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