Submission #284542

#	Time	Username	Problem	Language	Result	Execution time	Memory
284542		Pyqe	Kangaroo (CEOI16_kangaroo)	C++14	100 / 100	31 ms	384 KiB

kangaroo

#include <bits/stdc++.h>

using namespace std;

long long n,st,fn,dp[2][2069],dv=1e9+7;

int main()
{
	long long i,j,r,c=0;
	
	scanf("%lld%lld%lld",&n,&st,&fn);
	dp[0][0]=1;
	for(i=1;i<=n;i++)
	{
		for(j=1;j<=n;j++)
		{
			if(i!=st&&i!=fn)
			{
				dp[1][j]=(dp[0][j-1]*(j-c)+dp[0][j+1]*j)%dv;
			}
			else
			{
				dp[1][j]=dp[0][j];
				dp[1][j]=(dp[1][j]+dp[0][j-1])%dv;
			}
		}
		c+=i==st||i==fn;
		for(j=0;j<=n;j++)
		{
			dp[0][j]=dp[1][j];
			dp[1][j]=0;
		}
	}
	printf("%lld\n",dp[0][1]);
}

Compilation message (stderr)

kangaroo.cpp: In function 'int main()':
kangaroo.cpp:9:16: warning: unused variable 'r' [-Wunused-variable]
    9 |  long long i,j,r,c=0;
      |                ^
kangaroo.cpp:11:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   11 |  scanf("%lld%lld%lld",&n,&st,&fn);
      |  ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~

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