Submission #1193901

#	Time	Username	Problem	Language	Result	Execution time	Memory
1193901		MuhammadSaram	캥거루 (CEOI16_kangaroo)	C++20	100 / 100	51 ms	55112 KiB

kangaroo

#include <bits/stdc++.h>

using namespace std;

#define int long long

const int M = 2000 + 2, mod = 1e9 + 7;

int dp[M][M][3];

signed main()
{
	int n,s,e;
	cin>>n>>s>>e;
	dp[1][1][(s==1 or e==1)]=1;
	for (int i=2;i<=n;i++)
		for (int j=1;j<=i;j++)
		{
			if (i==s or i==e)
				for (int k=1;k<=2;k++)
					dp[i][j][k]=(dp[i-1][j-1][k-1]+dp[i-1][j][k-1])%mod;
			else
				for (int k=0;k<=2;k++)
					dp[i][j][k]=(dp[i-1][j-1][k]*(j-k)*(j>=k)+dp[i-1][j+1][k]*j)%mod;
		}
	cout<<dp[n][1][2]<<endl;

	return 0;	
}

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