Submission #730343

#	Time	Username	Problem	Language	Result	Execution time	Memory
730343		n0sk1ll	Skyscraper (JOI16_skyscraper)	C++17	100 / 100	325 ms	97728 KiB

skyscraper

#include <bits/stdc++.h>

#define FAST ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);cerr.tie(0)
#define mp make_pair
#define xx first
#define yy second
#define pb push_back
#define pf push_front
#define popb pop_back
#define popf pop_front
#define all(x) x.begin(),x.end()
#define ff(i,a,b) for (int i = a; i < b; i++)
#define fff(i,a,b) for (int i = a; i <= b; i++)
#define bff(i,a,b) for (int i = b-1; i >= a; i--)
#define bfff(i,a,b) for (int i = b; i >= a; i--)

using namespace std;
long double typedef ld;
unsigned int typedef ui;
long long int typedef li;
pair<int,int> typedef pii;
pair<li,li> typedef pli;
pair<ld,ld> typedef pld;
vector<vector<int>> typedef graph;
unsigned long long int typedef ull;
//const int mod = 998244353;
const int mod = 1000000007;







//Note to self: Check for overflow

int a[103];
int dp[103][103][1003][2][2];

int main()
{
    FAST;

    int n,L; cin>>n>>L;
    fff(i,1,n) cin>>a[i];
    sort(a+1,a+n+1),a[n+1]=mod;
    if (n==1) return cout<<1,0;

    dp[0][0][0][0][0]=1;
    fff(i,1,n) fff(j,1,n) fff(s,0,L)
    {
        li prevsum;

        prevsum=s-(li)(2*j)*(a[i+1]-a[i]);
        if (prevsum>=0)
        {
            (dp[i][j][s][0][0]+=dp[i-1][j-1][prevsum][0][0])%=mod;
            (dp[i][j][s][0][0]+=(li)2*j*dp[i-1][j][prevsum][0][0]%mod)%=mod;
            (dp[i][j][s][0][0]+=(li)j*(j+1)*dp[i-1][j+1][prevsum][0][0]%mod)%=mod;
        }

        prevsum=s-(li)(2*j-1)*(a[i+1]-a[i]);
        if (prevsum>=0)
        {
            (dp[i][j][s][0][1]+=dp[i-1][j-1][prevsum][0][1])%=mod;
            (dp[i][j][s][0][1]+=(li)(2*j-1)*dp[i-1][j][prevsum][0][1]%mod)%=mod;
            (dp[i][j][s][0][1]+=(li)(j*(j+1)-j)*dp[i-1][j+1][prevsum][0][1]%mod)%=mod;
                (dp[i][j][s][0][1]+=dp[i-1][j-1][prevsum][0][0])%=mod;
                (dp[i][j][s][0][1]+=(li)j*dp[i-1][j][prevsum][0][0]%mod)%=mod;
        }

        prevsum=s-(li)(2*j-1)*(a[i+1]-a[i]);
        if (prevsum>=0)
        {
            (dp[i][j][s][1][0]+=dp[i-1][j-1][prevsum][1][0])%=mod;
            (dp[i][j][s][1][0]+=(li)(2*j-1)*dp[i-1][j][prevsum][1][0]%mod)%=mod;
            (dp[i][j][s][1][0]+=(li)(j*(j+1)-j)*dp[i-1][j+1][prevsum][1][0]%mod)%=mod;
                (dp[i][j][s][1][0]+=dp[i-1][j-1][prevsum][0][0])%=mod;
                (dp[i][j][s][1][0]+=(li)j*dp[i-1][j][prevsum][0][0]%mod)%=mod;
        }

        prevsum=s-(li)(2*j-2)*(a[i+1]-a[i]);
        if (prevsum>=0)
        {
            (dp[i][j][s][1][1]+=dp[i-1][j-1][prevsum][1][1])%=mod;
            (dp[i][j][s][1][1]+=(li)(2*j-2)*dp[i-1][j][prevsum][1][1]%mod)%=mod;
            (dp[i][j][s][1][1]+=(li)(j*(j+1)-2*j)*dp[i-1][j+1][prevsum][1][1]%mod)%=mod;
                (dp[i][j][s][1][1]+=dp[i-1][j-1][prevsum][0][1])%=mod;
                (dp[i][j][s][1][1]+=dp[i-1][j-1][prevsum][1][0])%=mod;
                (dp[i][j][s][1][1]+=(li)(j-1)*dp[i-1][j][prevsum][0][1]%mod)%=mod;
                (dp[i][j][s][1][1]+=(li)(j-1)*dp[i-1][j][prevsum][1][0]%mod)%=mod;
                    if (i==n && j==1)
                    {
                        (dp[i][j][s][1][1]+=dp[i-1][j+1][prevsum][1][1])%=mod;
                            (dp[i][j][s][1][1]+=dp[i-1][j][prevsum][1][0])%=mod;
                            (dp[i][j][s][1][1]+=dp[i-1][j][prevsum][0][1])%=mod;
                    }
        }
    }

    int ans=0;
    fff(s,0,L) (ans+=dp[n][1][s][1][1])%=mod;
    cout<<ans<<"\n";
}

//Note to self: Check for overflow

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