mirror of
https://github.com/Kiritow/OJ-Problems-Source.git
synced 2024-03-22 13:11:29 +08:00
26 lines
442 B
C++
26 lines
442 B
C++
#include<stdio.h>
|
|
int con(int n,int m)
|
|
{
|
|
__int64 a=1,b=1,i;
|
|
for(i=1;i<=m;i++,n--)
|
|
{
|
|
b*=i;a*=n;
|
|
}
|
|
return a/b;
|
|
}
|
|
int main()
|
|
{
|
|
int i,n;
|
|
__int64 t,a[13];
|
|
a[0]=1;a[1]=0;a[2]=1;a[3]=2;
|
|
for(i=4;i<=12;i++)
|
|
a[i]=(i-1)*(a[i-1]+a[i-2]);
|
|
while(scanf("%d",&n)!=EOF&&n!=0)
|
|
{
|
|
t=0;
|
|
for(i=0;i<=n/2;i++)
|
|
t+=a[i]*con(n,i);
|
|
printf("%I64d\n",t);
|
|
}
|
|
}
|