代码如下，有俩ac...

#include <stdio.h>
int main (){
    int n,k,i,ia;
    double suma,sumb;
    scanf ("%d%d",&n,&k);
    for (i=1;i<=n;i++){
        if (i%k!=0){
            suma+=i;
            ia=ia+1;
        }
        if (i%k==0){
            sumb+=i;
        }
    }
    double ava=suma*1.0/ia;
    double avb=sumb*1.0/(n-ia);
    printf ("%.1lf %.1lf",ava,avb);
    return 0;
}