题解
- 这题算的久,码的短
- 好好算,其实不难,注意一些细节
代码
1 #include <cstdio> 2 #define ll long long 3 using namespace std; 4 const int a[8][2]={{2,1572858},{0,96},{2,18},{2,24576-6},{0,12},{0,6},{0,96},{2,1073741826-6}}; 5 int n,k; 6 int main() 7 { 8 freopen("color.in","r",stdin),freopen("color.out","w",stdout),scanf("%d%d",&n,&k); 9 int x=k*(k-1)/2,y=k*(k-1)*(k-2)/6; 10 printf("%lld\n",(ll)x*a[n-1][0]+(ll)y*a[n-1][1]); 11 return 0; 12 }