Train Problem II

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           using namespace std;const int INF=0x3f3f3f3f;#define mem(x,y) memset(x,y,sizeof(x))#define SI(x) scanf("%d",&x)#define PI(x) printf("%d",x)int N;//ｈ( n ) = ( ( 4*n-2 )/( n+1 )*h( n-1 ) );int ans[110][110];void db(){ ans[0][0]=1; ans[0][1]=1; ans[1][0]=1; ans[1][1]=1; int len=1,yu=0; for(int i=2;i<=100;i++){ for(int j=1;j<=len;j++){ int t=ans[i-1][j]*(4*i-2)+yu; yu=t/10; ans[i][j]=t%10; } while(yu){ ans[i][++len]=yu%10; yu/=10; } for(int j=len;j>=1;j--){ int t=ans[i][j]+yu*10; ans[i][j]=t/(i+1); yu=t%(i+1); } while(!ans[i][len])len--; ans[i][0]=len; }}int main(){ mem(ans,0); db(); while(~SI(N)){ for(int i=ans[N][0];i>=1;i--)printf("%d",ans[N][i]); puts(""); } return 0;}