Submission #76735

#	Time	Username	Problem	Language	Result	Execution time	Memory
76735		vex	Boat (APIO16_boat)	C++14	9 / 100	311 ms	4740 KiB

boat

#include <bits/stdc++.h>
#define maxn 505
#define f first
#define s second
#define pii pair<int,int>
#define mod (long long)(1e9 + 7)
using namespace std;

int n;
int a[maxn][2];
pii d[2*maxn];
int pl[maxn];
int pr[maxn];
long long dp[2*maxn][maxn];

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);

    cin>>n;
    for(int i=1;i<=n;i++)
    {
        cin>>a[i][0]>>a[i][1];
        d[2*i-1]={a[i][0],0};
        d[2*i]={a[i][1],1};

        pl[i]=a[i][0];
        pr[i]=a[i][1];
    }

    sort(d+1,d+2*n+1);

    for(int i=1;i<=n;i++)dp[0][i]=0;
    dp[0][0]=1;
    for(int j=1;j<=n;j++)if(pl[j]==d[1].f)dp[0][j]=1;

    for(int i=1;i<=2*n-1;i++)
    {
        dp[i][0]=1;
        for(int j=1;j<=n;j++)
        {
            dp[i][j]=dp[i-1][j];
            int dod=0;

            if(d[i].f==d[i+1].f)continue;

            if(pl[j]==d[i+1].f)dod=1;
            else if(pl[j]<=d[i].f && d[i+1].f<=pr[j])dod=d[i+1].f-d[i].f;
            else continue;

            //cout<<i<<"    "<<j<<" "<<dod<<endl;

            for(int k=0;k<j;k++)
            {
                dp[i][j]+=dp[i-1][k]*dod;
                dp[i][j]%=mod;

                if(pl[j]==d[i+1].f && pl[k]<=d[i].f && d[i+1].f<=pr[k])
                {
                    dp[i][j]+=(dp[i][k]-dp[i-1][k])*(d[i+1].f-d[i].f-1)/(d[i+1].f-d[i].f);
                    dp[i][j]%=mod;
                }
            }
        }
    }

    long long sol=0;
    for(int i=1;i<=n;i++)
    {
        sol+=dp[2*n-1][i];
        sol%=mod;
    }

    //for(int i=1;i<=2*n;i++)cout<<d[i].f<<" "<<d[i].s<<endl;cout<<endl;
    /*for(int i=1;i<=n;i++)cout<<i<<"   "<<pl[i]<<" "<<pr[i]<<endl;cout<<endl;
    for(int i=0;i<=2*n-1;i++)
    {
        cout<<i<<"    ";
        for(int j=0;j<=n;j++)cout<<dp[i][j]<<" ";
        cout<<endl;
    }*/

    cout<<sol<<endl;
    return 0;
}

• Subtask 1: 9 / 9
• Subtask 2: 0 / 22
• Subtask 3: 0 / 27
• Subtask 4: 0 / 42