Submission #669097

#	Time	Username	Problem	Language	Result	Execution time	Memory
669097		groshi	Kangaroo (CEOI16_kangaroo)	C++17	100 / 100	98 ms	31744 KiB

kangaroo

#include<iostream>
#define int long long
using namespace std;
int dp[2010][2010];
int mod=1e9+7;
int32_t main()
{
    cin.tie(0);
    cout.tie(0);
    ios_base::sync_with_stdio(0);
    int n,a,b;
    cin>>n>>a>>b;
    dp[1][1]=1;
    for(int i=2;i<=n;i++)
    {
        for(int j=1;j<=n;j++)
        {
            if(i==a || i==b)
                dp[i][j]+=dp[i-1][j-1]+dp[i-1][j];
            else dp[i][j]+=dp[i-1][j+1]*j+dp[i-1][j-1]*(((j-(i>a)-(i>b)+mod*mod))%mod);
            dp[i][j]+=mod*mod;
            dp[i][j]%=mod;
        }
    }
    cout<<dp[n][1];
    return 0;
}

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