Submission #1124755

#	Time	Username	Problem	Language	Result	Execution time	Memory
1124755		Icelast	Skyscraper (JOI16_skyscraper)	C++17	100 / 100	104 ms	50864 KiB

skyscraper

#include <iostream>
#include <bits/stdc++.h>
#define ll long long
#define int long long
using namespace std;
const ll maxn = 2*1e5+5, INF = 4e18+9, mod = 1e9+7;
ll f[102][102][1002][3];
void solve(){
    int n, s;
    cin >> n >> s;
    vector<ll> h(n+1);
    for(int i = 1; i <= n; i++){
        cin >> h[i];
    }
    if(n == 1){
        cout << 1;
        return;
    }
    sort(h.begin()+1, h.end());
    f[0][0][0][0] = 1;
    h.push_back(10000);
    for(int i = 1; i <= n; i++){
        for(int j = 1; j <= i; j++){
            for(int k = 0; k <= s; k++){
                for(int m = 0; m <= 2; m++){
                    ll cost = (j*2-m)*(h[i+1]-h[i]);
                    if(k-cost < 0 || i+j+1-m > n) continue;
                    f[i][j][k][m] += f[i-1][j-1][k-cost][m];

                    if(m) f[i][j][k][m] += f[i-1][j-1][k-cost][m-1] * (3-m) % mod;

                    f[i][j][k][m] += f[i-1][j][k-cost][m] * (j*2-m) % mod;

                    if(m == 1){
                        f[i][j][k][m] += f[i-1][j][k-cost][m-1] * (j*2);
                    }else if(m == 2){
                        if(i == n){
                            f[i][j][k][m] += f[i-1][j][k-cost][m-1];
                        }else if(j > 1){
                            f[i][j][k][m] += f[i-1][j][k-cost][m-1] * (j-1) % mod;
                        }

                    }

                    if(m == 0){
                        f[i][j][k][m] += f[i-1][j+1][k-cost][m] * (j*(j+1)%mod) % mod;
                    }else if(m == 1){
                        f[i][j][k][m] += f[i-1][j+1][k-cost][m] * (j*j) % mod;
                    }else if(m == 2){
                        if(i == n){
                            f[i][j][k][m] += f[i-1][j+1][k-cost][m];
                        }else{
                            f[i][j][k][m] += f[i-1][j+1][k-cost][m] * (j*(j-1)%mod);
                        }
                    }
                    f[i][j][k][m] %= mod;
                }
            }
        }
    }
    ll ans = 0;
    for(int k = 0; k <= s; k++){
        ans += f[n][1][k][2];
    }
    ans %= mod;
    cout << ans;
}
signed main(){
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    solve();
}

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