Banker's algorithm

#include <iostream>
#include <valarray>
#include <vector>
#include <list>
using namespace std;

int main()
{
    using namespace std;
    typedef list<vector<valarray<int> > > Matrix;
    enum : Matrix::size_type { Allocation = 0, Max = 1, Need = 1 };
    Matrix mat {
        //  Allocation  ,   Max / Need
        { { 0, 0, 1, 4 }, { 0, 6, 5, 6 } },
        { { 1, 4, 3, 2 }, { 1, 9, 4, 2 } },
        { { 1, 3, 5, 4 }, { 1, 3, 5, 6 } },
        { { 1, 0, 0, 0 }, { 1, 7, 5, 9 } }
    };
    valarray<int> Available { 1, 5, 2, 0 };
    for_each( mat.begin(), mat.end(), [] (Matrix::reference val) { val[Need] = val[Max] - val[Allocation]; } );
    Matrix::iterator it;
    while ( ( it = find_if( mat.begin(), mat.end(),
            [&Available] (Matrix::const_reference val) { return (val[Need] <= Available).min() == true; } ) ) != mat.end() )
        Available += (*it)[Allocation], mat.erase(it), it = mat.begin();
    cout << (mat.empty() ? "Safe!" : "Unsafe!") << endl;
}