Google Code Jam Round 2 2013 Problem B in O(1)

#include <limits.h>
#include <stdio.h>

static inline long long min(long long a, long long b)
{ return a < b ? a : b; }

static inline int floor_log2(long long x)
{ return !x ? -1 : (int) sizeof x * CHAR_BIT - 1 - __builtin_clzll(x); }

int main(void)
{
    int T;
    scanf("%d", &T);

    for (int iT = 1; iT <= T; ++iT)
    {
        int N;
        long long P;
        scanf("%d%lld", &N, &P);

        long long may = (1LL << N) - (1LL << N - floor_log2(P));
        long long must = min((1LL << N - floor_log2((1LL << N) - P)) - 2, (1LL << N) - 1);
        printf("Case #%d: %lld %lld\n", iT, must, may);
    }
}