暑期个人赛第四场
题意:把n个求分给k个颜色,
思路:转化一下,将球的n-1个空隙插上隔板,那么答案就是c(n-1,k-1);
代码如下:
#include <cstdio>
long long c(int n, int k)
{
if(n-k<k) k = n-k;
double ans = 1;
for(int i = 1; i <= k; i++) ans*=1.0*(n-i+1)/i;
return (long long)(ans+0.5);
}
int main ()
{
int n, k, t;
scanf("%d", &t);
while(t--)
{
scanf("%d %d",&n,&k);
printf("%lld\n", c(n-1,k-1));
}
return 0;
}
代码如下:
#include <cstdio>
double c(int n, int k)
{
if(n-k<k) k = n-k;
double c = 1.0;
for(int i = 1; i <= k; ++i) c = c*(n-i+1)/i;
return c;
}
int main ()
{
int n, k, t;
scanf("%d", &t);
while(t--)
{
scanf("%d %d",&n,&k);
printf("%lld\n", c(n-1,k-1));
}
return 0;
}