Submission #912501

#	Time	Username	Problem	Language	Result	Execution time	Memory
912501		fanwen	Skyscraper (JOI16_skyscraper)	C++17	100 / 100	34 ms	28844 KiB

skyscraper

#include <bits/stdc++.h>

using namespace std;

const int Mod = 1e9 + 7;

int n, L, a[101];
long long dp[101][101][1005][3];

signed main() {
    cin >> n >> L;
    for (int i = 1; i <= n; ++i) cin >> a[i];
    sort(a + 1, a + n + 1);
    if(n == 1) {
        cout << 1;
        return 0;
    }

    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 e = 0; e < 3; ++e) {
                    if(dp[i][j][k][e] == 0) continue;
                    int new_cost = k + (a[i + 1] - a[i]) * (2 * j - e);
                    if(new_cost > L) continue;
                    (dp[i + 1][j + 1][new_cost][e] += dp[i][j][k][e] * (j + 1 - e)) %= Mod;
                    (dp[i + 1][j][new_cost][e] += dp[i][j][k][e] * (2 * j - e)) %= Mod; 
                    (dp[i + 1][j - 1][new_cost][e] += dp[i][j][k][e] * (j - 1)) %= Mod;
                    if(e < 2) {
                        (dp[i + 1][j + 1][new_cost][e + 1] += dp[i][j][k][e] * (2 - e)) %= Mod;
                        (dp[i + 1][j][new_cost][e + 1] += dp[i][j][k][e] * (2 - e)) %= Mod;
                    }
                }
            }
        }
    }

    long long ans = 0;

    for (int i = 0; i <= L; ++i) {
        ans += dp[n][1][i][2];
        ans %= Mod;
    }
    cout << ans;

}

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