Submission #377224

#	Time	Username	Problem	Language	Result	Execution time	Memory
377224		CaroLinda	Kangaroo (CEOI16_kangaroo)	C++14	100 / 100	28 ms	23020 KiB

kangaroo

#include <bits/stdc++.h>

const int MAXN = 2010 ;
const int MOD = 1e9+7 ;

using namespace std ;

int N , S , T ;
long long dp[MAXN][MAXN] ;

int main()
{
	scanf("%d %d %d", &N , &S, &T ) ;

	if( S > T ) swap(S,T) ;

	dp[0][1] = 1 ;

	for(int i = 1 ; i < N ; i++ )
		for(int j= 1 ; j <= N-i ; j++ )
		{
			long long &ptr = dp[i][j] ;
			long long fat ;

			if( i == T || i == S )
			{
				ptr = dp[i-1][j+1] + dp[i-1][j] ;
				if( ptr >= MOD ) ptr -= MOD ;
				continue ;
			}
		
			//creating new component
			fat = (j-1) + ( i > S ) + (i > T ) ;
			ptr = (fat * dp[i-1][j+1] ) % MOD ;

			//joining two components
			ptr += (dp[i-1][j-1] * (j-1) ) % MOD ;
			ptr %= MOD ;

		}

	long long ans = dp[N-1][1] ;

	printf("%lld\n", ans ) ;
}

Compilation message (stderr)

kangaroo.cpp: In function 'int main()':
kangaroo.cpp:13:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   13 |  scanf("%d %d %d", &N , &S, &T ) ;
      |  ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~

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