Submission #1276685

#	Time	Username	Problem	Language	Result	Execution time	Memory
1276685		Buivietthanh	Linear Garden (IOI08_linear_garden)	C++20	100 / 100	58 ms	36456 KiB

linear_garden

#include<bits/stdc++.h>
using namespace std;
#define ll long long
int n,m,dp[1000003][3][3];
char a[1000003];
int main()
{
    srand(time(NULL));
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    //freopen("inp.INP","r",stdin);
    //freopen("out.OUT","w",stdout);
    cin>>n>>m;
    for (int i=1;i<=n;i++) cin>>a[i];
    dp[n+1][2][0]=1;
    for (int i=n;i>=1;i--)
    {
        for (int minn=-2;minn<=0;minn++)
        {
            for (int maxx=0;maxx<=2;maxx++)
            {
                ll min1=min(minn+1,0),max1=maxx+1;
                if (min1>=-2 && max1<=2)
                dp[i][min1+2][max1]+=dp[i+1][minn+2][maxx],dp[i][min1+2][max1]%=m;
                min1=minn-1,max1=max(maxx-1,0);
                if (min1>=-2 && max1<=2)
                dp[i][min1+2][max1]+=dp[i+1][minn+2][maxx],dp[i][min1+2][max1]%=m;
            }
        }
    }
    ll minn=0,maxx=0,sum=0;
    for (int i=1;i<=n;i++)
    {
       //cout<<i<<' '<<sum<<endl;
        ll p=(a[i]=='P'?1:-1);
        ll min1=min(minn+p,min(p,(ll)0));
        ll max1=max(maxx+p,max(p,(ll)0));
        if (min1<-2)
        {
            sum=0;
            break;
        }
        if (max1>2)
        {
            minn=min(minn-1,(ll)-1);
            maxx=max(maxx-1,(ll)0);
            if (minn<-2)
            {
                sum=0;
                break;
            }
            continue;
        }
        if (a[i]=='P' && minn-1>=-2)
        {
            minn--;
            maxx=max(maxx-1,(ll)0);
            for (int u=-2;u<=0;u++)
            {
                for (int v=0;v<=2;v++)
                {
                    if (minn+u>=-2 && maxx+v<=2)
                    {
                        sum+=dp[i+1][u+2][v];
                        sum%=m;
                    }
                }
            }
        }
        if (i==n) sum=(sum+1)%m;
        minn=min1;
        maxx=max1;
    }
    cout<<sum;
}

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• Subtask 2: 2 / 2
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