特别注意:h的类型应该是double
#include <bits/stdc++.h>
using namespace std;
int t, n;
double h;
int main() {
scanf("%d", &t);
while(t --) {
scanf("%lf%d", &h, &n);
double summ = h * 1.0;
for (int i = 1; i < n; i++) {
summ += h;
h /= 2;
}
printf("%.2lf\n", summ);
}
return 0;
}