Submission #127629

#	Time	Username	Problem	Language	Result	Execution time	Memory
127629		TadijaSebez	캥거루 (CEOI16_kangaroo)	C++11	51 / 100	2048 ms	20908 KiB

kangaroo

#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
#include <bits/stdc++.h>
using namespace std;
const int mod=1e9+7;
const int N=2005;
int add(int x, int y){ x+=y;return x>=mod?x-mod:x;}
void ADD(int &x, int y){ x=add(x,y);}
int sub(int x, int y){ x-=y;return x<0?x+mod:x;}
void SUB(int &x, int y){ x=sub(x,y);}
int dp[N][N][2],sum[N][N][2];
int Get(int i, int l, int r, int t)
{
	int x=sum[i][r][t]-sum[i][l-1][t];
	if(x<0) x+=mod;
	return x;
}
int main()
{
	int n,cs,cf;
	scanf("%i %i %i",&n,&cs,&cf);
	dp[1][1][0]=dp[1][1][1]=1;
	for(int l=2;l<=n;++l)
	{
		for(int i=1;i<=l-1;++i)
			for(int j=1;j<=l-1;++j)
			{
				sum[i][j][0]=sum[i][j-1][0]+dp[i][j][0];
				if(sum[i][j][0]>=mod) sum[i][j][0]-=mod;
				sum[i][j][1]=sum[i][j-1][1]+dp[i][j][1];
				if(sum[i][j][1]>=mod) sum[i][j][1]-=mod;
			}
		for(int i=1;i<=l;++i)
			for(int j=1;j<=l;++j)
			{
				if(i!=j)
				{
					dp[i][j][0]=Get(i-(i>j),1,j-1,1);
					dp[i][j][1]=Get(i-(i>j),j,l-1,0);
				}
				else dp[i][j][0]=dp[i][j][1]=0;
			}
	}
	int ans=add(dp[cs][cf][0],dp[cs][cf][1]);
	printf("%i\n",ans);
	return 0;
}

Compilation message (stderr)

kangaroo.cpp: In function 'int main()':
kangaroo.cpp:21:7: 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: 0 / 49