範例程式碼 uva11636

//uva11636
#include<cstdio>

int main()
{
    int a[20] = {0}, cas = 1, n;

    a[0] = 1, a[1] = 2;
    for (int i = 2; i<20; i++)
        a[i] = a[i-1]*2;

    while (scanf("%d", &n) && n >= 0){
        for (int i = 0; i<20; i++){
            if (n <= a[i]){
                printf("Case %d: %d\n", cas, i);
                break;
            }
        }
        cas++;
    }
}