PriQNoHeap.cs

class PriorityQueue
{
    private Dictionary<int, int> _frequencies;

    public PriorityQueue()
    {
        _frequencies = new Dictionary<int, int>();
    }

    public void Add(int item)
    {
        if (_frequencies.ContainsKey(item))
        {
            _frequencies[item]++;
        }
        else
        {
            _frequencies.Add(item, 1);
        }         
    }

    public int Pop()
    {
        int max = 0;
        int key = -1;
        foreach (var pair in _frequencies)
        {
            if (pair.Value > max)
            {
                max = pair.Value;
                key = pair.Key;
            }
        }
        _frequencies.Remove(key);
        return key;
    }
}