Submission #1033756

#	Time	Username	Problem	Language	Result	Execution time	Memory
1033756		juicy	Skyscraper (JOI16_skyscraper)	C++17	100 / 100	74 ms	27888 KiB

skyscraper

#include <bits/stdc++.h>

using namespace std;

#ifdef LOCAL
#include "debug.h"
#else
#define debug(...) 42
#endif

const int N = 105, L = 1005, MD = 1e9 + 7;

void add(int &a, int b) {
	if ((a += b) >= MD) {
		a -= MD;
	}
}

int n, l;
int a[N], dp[N][N][L][3];

int main() {
	ios::sync_with_stdio(false); cin.tie(nullptr);

	cin >> n >> l;
	if (n == 1) {
		cout << 1;
		exit(0);
	}
	for (int i = 1; i <= n; ++i) {
		cin >> a[i];
	}
	a[n + 1] = 10000; 
	dp[0][0][0][0] = 1;
	sort(a + 1, a + n + 1);
	for (int i = 1; i <= n; ++i) {
		for (int j = 1; j <= i; ++j) {
			for (int k = 0; k <= l; ++k) {
				for (int m = 0; m < 3; ++m) {
					int dif = (a[i + 1] - a[i]) * (2 * j - m);
					int &res = dp[i][j][k][m];
					if (dif <= k && i + j + 1 - m <= n) {
						add(res, dp[i - 1][j - 1][k - dif][m]);
						add(res, (long long) (2 * j - m) * dp[i - 1][j][k - dif][m] % MD);
						if (m > 0) {
							add(res, (long long) (3 - m) * dp[i - 1][j - 1][k - dif][m - 1] % MD);
							if (m == 1) {
								add(res, 2LL * j * dp[i - 1][j][k - dif][m - 1] % MD);
							} else {
								if (i == n) {
									if (j == 1) {
										add(res, dp[i - 1][j][k - dif][m - 1]);
									}
								} else {
									add(res, (long long) (j - 1) * dp[i - 1][j][k - dif][m - 1] % MD);
								}
							}
						}
						if (m == 2) {
							if (i == n) {
								add(res, dp[i - 1][j + 1][k - dif][m]);
							} else {
								add(res, (long long) j * (j - 1) * dp[i - 1][j + 1][k - dif][m] % MD); 
							}
						} else if (m == 1) {
							add(res, (long long) j * j * dp[i - 1][j + 1][k - dif][m] % MD);
						} else {	
							add(res, (long long) j * (j + 1) * dp[i - 1][j + 1][k - dif][m] % MD);
						}
					}
				}
			}
		} 
	}
	int res = 0;
	for (int k = 0; k <= l; ++k) {
		add(res, dp[n][1][k][2]);
	}
	cout << res;
	return 0;
}

// Thanks Usaco!!!

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