Submission #127636

#	Time	Username	Problem	Language	Result	Execution time	Memory
127636		TadijaSebez	Kangaroo (CEOI16_kangaroo)	C++11	100 / 100	32 ms	15992 KiB

kangaroo

#include <bits/stdc++.h>
using namespace std;
#define ll long long
const int N=2005;
const int mod=1e9+7;
int add(int x, int y){ x+=y;return x>=mod?x-mod:x;}
int mul(int x, int y){ return (ll)x*y%mod;}
int dp[N][N];
int main()
{
	int n,cs,cf;
	scanf("%i %i %i",&n,&cs,&cf);
	dp[0][0]=1;
	for(int i=1;i<=n;i++) for(int j=1;j<=n;j++)
	{
		if(i==cs || i==cf) dp[i][j]=add(dp[i-1][j-1],dp[i-1][j]);
		else dp[i][j]=add(mul(dp[i-1][j+1],j),mul(dp[i-1][j-1],j-(i>cs)-(i>cf)));
	}
	printf("%i\n",dp[n][1]);
	return 0;
}

Compilation message (stderr)

kangaroo.cpp: In function 'int main()':
kangaroo.cpp:12:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%i %i %i",&n,&cs,&cf);
  ~~~~~^~~~~~~~~~~~~~~~~~~~~~~

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