HackerRank "Permutation game"

A typical game theory problem - Recursion + Memorized Search
http://justprogrammng.blogspot.com/2012/06/interviewstreet-challenges-permutation.html#.VlEMrvmrTIU

#include<iostream>
#include<set>
using namespace std;

//    Bit Ops Utils
int set(int a, int i)
{
    return  a |  << i;
}
int unset(int a, int i)
{
    return a & (~( << i));
}
int get(int a, int i)
{
    return ((a&( << i)) >> i);
}

//
int array[]; // for results record
int a[];

//
int play(int a[], int n, int r)
{
    if (array[r] != -) return array[r];

    // Check increase
    int last = , i;
    for (i = ; i < n; i++)
    {
        if (get(r, i))
        {
            if (a[i]>last)    last = a[i];
            else    break;
        }
    }
    if (i == n)
    {
        array[r] = ;
        return ;
    }

    //    Recursively check each possibility
    int rec[] = { ,  };
    for (int i = ; i<n; i++)
    {
        if (get(r, i))
        {
            int ret = play(a, n, unset(r, i));
            rec[ret] = ;
        }
    }
    array[r] = rec[];

    return array[r];

}

int main()
{
    int T;
    cin >> T;

    while (T--)
    {
        for (int i = ; i < ; i++)
            array[i] = -;

        int n; cin >> n;
        for (int i = ; i < n; i++)
            cin >> a[i];

        int res = play(a, n, ( << n) - );
        if (!res)    cout << "Bob\n";
        else        cout << "Alice\n";
    }
}