Submission #1285545

#	Time	Username	Problem	Language	Result	Execution time	Memory
1285545		Faisal_Saqib	Skyscraper (JOI16_skyscraper)	C++20	100 / 100	169 ms	163112 KiB

skyscraper

#include <bits/stdc++.h>
using namespace std;
#define ll long long
const int N=102,L=1002,mod=1e9+7;
ll dp[N][N][L][4],a[N];
int main()
{
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);   
    ll n,l;
    cin>>n>>l;
    for(int i=1;i<=n;i++)
    {
        cin>>a[i];
    }
    if(n==1)
    {
        cout<<1<<endl;
        return 0;
    }
    sort(a+1,a+1+n);
    a[n+1]=a[n];
    dp[0][0][0][0]=1;
    for(int i=1;i<=n;i++)
    {
        for(int j=1;j<=n;j++)
        {
            for(int k=0;k<=l;k++)
            {
                for(int m=0;m<3;m++)
                {
                    ll ac=(a[i+1]-a[i])*(2*j-m);// additonal cost
                    if(k<ac)continue;
                    // new component not at the end
                    dp[i][j][k][m]+=dp[i-1][j-1][k-ac][m];
                    // new component at one of the end
                    if(m>0)
                    {
                        dp[i][j][k][m]+=(3-m)*dp[i-1][j-1][k-ac][m-1];
                    }

                    // add to one of the component but not any end
                    dp[i][j][k][m]+=(2*j-m)*dp[i-1][j][k-ac][m];
                    // add to component and making it end
                    if(m==1)
                    {
                        dp[i][j][k][m]+=j*2*dp[i-1][j][k-ac][m-1];
                    }
                    else if(m==2)
                    {
                        if(j==1)
                        {
                            if(i==n)
                            {
                                dp[i][j][k][m]+=dp[i-1][j][k-ac][m-1];
                            }
                        }
                        else
                        {
                            dp[i][j][k][m]+=(j-1)*dp[i-1][j][k-ac][m-1];
                        }
                    }
                    else
                    {
                        // m==0 not pos
                    }


                    // merge two components
                    // which two to merge
                    // if m==2
                    if(m==2)
                    {
                        if(j==1)
                        {
                            // we merge one containing the first endpoint and the last endpoint
                            if(i==n)
                            {
                                dp[i][j][k][m]+=dp[i-1][j+1][k-ac][m];
                            }
                        }
                        else
                        {
                            // we can't merge the first and the last with each other
                            dp[i][j][k][m]+=((j-1)*(j-2)+2*(j-1))*(dp[i-1][j+1][k-ac][m]);
                        }
                    }
                    else if(m==1)
                    {
                        // j + (j-1)*j = j*j
                        dp[i][j][k][m]+=(j*j)*dp[i-1][j+1][k-ac][m];
                    }
                    else
                    {
                        dp[i][j][k][m]+=(j+1)*(j)*dp[i-1][j+1][k-ac][m];
                    }

                    dp[i][j][k][m]%=mod;
                }
            }
        }
    }
    ll ans=0;
    for(int i=0;i<=l;i++)
    {
        ans+=dp[n][1][i][2];
        ans%=mod;
    }
    cout<<ans<<endl;
}

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