Submission #1193905

#	Time	Username	Problem	Language	Result	Execution time	Memory
1193905		Muhammad_Aneeq	Kangaroo (CEOI16_kangaroo)	C++20	100 / 100	41 ms	55112 KiB

kangaroo

/*
بسم الله الرحمن الرحيم
Author:
                          (:Muhammad Aneeq:)
*/

#include <iostream>
#warning check the output
using namespace std;
int const N=2e3+10,mod=1e9+7;
long long dp[N][N][3]={};
inline void solve()
{
    int n;
    int st,en;
    cin>>n;
    cin>>st>>en;
    dp[1][1][(st==1)+(en==1)]=1;
    for (int i=1;i<n;i++)
    {
        for (long long j=1;j<=i;j++)
        {
            if (i+1==st||i+1==en)
            {
                for (int k=1;k<=2;k++)
                {
                    dp[i+1][j+1][k]+=(dp[i][j][k-1]);
                    dp[i+1][j][k]+=(dp[i][j][k-1]);
                    dp[i+1][j+1][k]%=mod;
                    dp[i+1][j][k]%=mod;
                }
            }
            else
            {
                for (int k=0;k<3;k++)
                {
                    dp[i+1][j+1][k]+=(dp[i][j][k]*(j+1-k));
                    dp[i+1][j-1][k]+=(dp[i][j][k]*(j-1));
                    dp[i+1][j+1][k]%=mod;
                    dp[i+1][j-1][k]%=mod;
                }
            }
        }
    }
    cout<<dp[n][1][2]<<endl;
}
int main()
{
    ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);
    int t=1;
    for (int i=1;i<=t;i++)
    {
        solve();
    }
}

Compilation message (stderr)

kangaroo.cpp:8:2: warning: #warning check the output [-Wcpp]
    8 | #warning check the output
      |  ^~~~~~~

• Subtask 1: 6 / 6
• Subtask 2: 30 / 30
• Subtask 3: 15 / 15
• Subtask 4: 49 / 49