Submission #1845535

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Source Code Expand

#include<cstdio>
using namespace std;
const int N=3030,P=1000000007;
int i,j,k,n,m,L,R,t,ans;
int f[2][2][N];
void Up(int &x,int y) {
	x=(x+y)%P;
}
int main() {
	scanf("%d%d",&n,&m);
	L=1;R=0;
	for (i=1;i<=n;i++) f[R][0][i]=1;
	f[R][1][0]=1;
	for (i=1;i<=m;i++) {
		L^=1;R^=1;
		for (j=0;j<=n;j++) {
			if (f[L][0][j]) {
				t=f[L][0][j];
				if (j<n) Up(f[R][0][j+1],t),Up(f[R][0][j],t);
				if (j>1) Up(f[R][0][j-1],t),Up(f[R][0][j],t);
				if (j==1) Up(f[R][1][0],t),Up(f[R][1][1],t);
				f[L][0][j]=0;
			}
			if (f[L][1][j]) {
				t=f[L][1][j];
				if (j<n) Up(f[R][1][j+1],t),Up(f[R][1][j],t);
				if (j>0) Up(f[R][1][j-1],t),Up(f[R][1][j],t);
				f[L][1][j]=0;
			}
		}
	}
	for (i=0;i<=n;i++) Up(ans,f[R][1][i]);
	printf("%d\n",ans);
}

Submission Info

Compile Error

./Main.cpp: In function ‘int main()’:
./Main.cpp:10:21: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d",&n,&m);
                     ^

Judge Result