Submission #2124671

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Source Code Expand

#include <iostream>
#include <cstdio>

using namespace std;

const int P=1000000007;
const int N=2005;

int f[N][N][2];
int n,K,ans;

inline void update(int &x,int y){(x+=y)%=P;}

int main()
{
	//freopen("solitaire.in","r",stdin),freopen("solitaire.out","w",stdout);
	scanf("%d%d",&n,&K);
	f[n+1][0][0]=1;
	for (int i=n+1;i>=1;--i)
	{
		for (int j=n-1;j>=0;--j) update(f[i][j][0],f[i][j+1][0]);
		for (int j=0;i>1&&j<=n;++j)
			for (int k=0;k<2;++k)
				if (f[i][j][k])
				{
					update(f[i-1][j+1][1],f[i][j][k]);
					update(f[i-1][j][0],f[i][j][k]);
				}
	}
	ans=f[1][n-K][0];
	for (int i=1;i<=n-K-1;++i) (ans<<=1)%=P;
	printf("%d\n",ans);
	//fclose(stdin),fclose(stdout);
	return 0;
}

Submission Info

Compile Error

./Main.cpp: In function ‘int main()’:
./Main.cpp:17:21: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d",&n,&K);
                     ^

Judge Result