Submission #866846

#	Time	Username	Problem	Language	Result	Execution time	Memory
866846		prohacker	Skyscraper (JOI16_skyscraper)	C++14	100 / 100	125 ms	46164 KiB

skyscraper

#include <bits/stdc++.h>
#define ll long long
#define ld long double

using namespace std;

const int N = 105;
const int INF = INT_MAX;
const int mod = 1e9+7;

int n,lim,dp[N][N][1010][3],a[N];
int ans;

void add(int &x, const int y) {
    x += y;
    if(x >= mod) {
        x -= mod;
    }
}

signed main()
{
    if (fopen("task.inp", "r")) {
        freopen("task.inp", "r", stdin);
        freopen("task.out", "w", stdout);
    }
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    cin >> n >> lim;
    if(n == 1) {
        cout << 1;
        return 0;
    }
    for(int i = 1 ; i <= n ; i++) {
        cin >> a[i];
    }
    sort(a+1,a+n+1);
    a[n+1] = 10010;
    dp[0][0][0][0] = 1;
    for(int i = 1 ; i <= n ; i++) {
        for(int j = 1 ; j <= i ; j++) {
            for(int k = 0 ; k <= lim ; k++) {
                for(int m = 0 ; m <= 2 ; m++) {
                    int delta = (2*j-m)*(a[i+1]-a[i]);
                    if(delta > k) {
                        continue;
                    }
                    add(dp[i][j][k][m],dp[i-1][j-1][k-delta][m]);
                    add(dp[i][j][k][m],1LL*(2*j-m)*dp[i-1][j][k-delta][m]%mod);
                    if(m > 0) {
                        if(j > 0) {
                            add(dp[i][j][k][m],1LL*(3-m)*dp[i-1][j-1][k-delta][m-1]%mod);
                        }
                        if(m == 1) {
                            add(dp[i][j][k][m],1LL*2*j*dp[i-1][j][k-delta][m-1]%mod);
                        }
                        else {
                            if(i == n) {
                                add(dp[i][j][k][m],dp[i-1][j][k-delta][m-1]);
                            }
                            else {
                                if(j > 0) {
                                    add(dp[i][j][k][m],1LL*(j-1)*dp[i-1][j][k-delta][m-1]%mod);
                                }
                            }
                        }
                    }
                    if(m == 2) {
                        if(i == n) {
                            add(dp[i][j][k][m],dp[i-1][j+1][k-delta][m]);
                        }
                        else {
                            add(dp[i][j][k][m],1LL*j*(j-1)*dp[i-1][j+1][k-delta][m]%mod);
                        }
                    }
                    else if(m == 1) {
                        add(dp[i][j][k][m],1LL*j*j*dp[i-1][j+1][k-delta][m]%mod);
                    }
                    else {
                        add(dp[i][j][k][m],1LL*j*(j+1)*dp[i-1][j+1][k-delta][m]%mod);
                    }
                }
            }
        }
    }
    for(int i = 0 ; i <= lim ; i++) {
        add(ans,dp[n][1][i][2]);
    }
    cout << ans;
    return 0;
}

Compilation message (stderr)

skyscraper.cpp: In function 'int main()':
skyscraper.cpp:24:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   24 |         freopen("task.inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
skyscraper.cpp:25:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   25 |         freopen("task.out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

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