Submission #553195

#	Time	Username	Problem	Language	Result	Execution time	Memory
553195		Jomnoi	Skyscraper (JOI16_skyscraper)	C++17	15 / 100	1 ms	852 KiB

skyscraper

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

const int MAX_N = 105;
const int MAX_L = 1005;
const int MOD = 1e9 + 7;

int A[MAX_N];
int dp[MAX_N][MAX_N][MAX_L][3];

int main() {
	cin.tie(nullptr)->sync_with_stdio(false);
	int N, L;
	cin >> N >> L;
	for(int i = 1; i <= N; i++) {
		cin >> A[i];
	}

	if(N == 1) { // the answer will be 0, so 0 is strictly less than or equal to L
		cout << 0;
		return 0;
	}

	sort(A + 1, A + N + 1);

	dp[1][1][0][0] = 1;
	dp[1][1][0][1] = 2;
	for(int i = 1; i < N; i++) {
		for(int j = 1; j <= i; j++) {
			for(int k = 0; k <= L; k++) {
				for(int z = 0; z <= 2; z++) {
					int nk = k + (2 * j - z) * (A[i + 1] - A[i]);
					if(nk > L) {
						continue;
					}

					if(z < 2) { // add i to end point
						dp[i + 1][j][nk][z + 1] += 1ll*(2 - z) * dp[i][j][k][z] % MOD; // add i to the left or right most component to be an end point
						dp[i + 1][j][nk][z + 1] %= MOD;

						dp[i + 1][j + 1][nk][z + 1] = 1ll*(2 - z) * dp[i][j][k][z] % MOD; // create new component to the left or right most
						dp[i + 1][j + 1][nk][z + 1] %= MOD;
					}
					
					dp[i + 1][j][nk][z] += 1ll*(2 * j - z) * dp[i][j][k][z] % MOD; // add i to left or right most of some components
					dp[i + 1][j][nk][z] %= MOD;

					dp[i + 1][j + 1][nk][z] += 1ll*(j + 1 - z) * dp[i][j][k][z] % MOD; // create new component
					dp[i + 1][j + 1][nk][z] %= MOD;

					dp[i + 1][j - 1][nk][z] += 1ll*(j - 1) * dp[i][j][k][z] % MOD; // merge two components
					dp[i + 1][j - 1][nk][z] %= MOD;
				}
			}
		}
	}

	int ans = 0;
	for(int k = 0; k <= L; k++) {
		ans += dp[N][1][k][2];
		ans %= MOD;
	}
	cout << ans;
	return 0;
}

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