MinHeap.cs

    // Min Heap
    public class MinHeap<T> where T: IComparable
    {
        private List<T> items = new List<T>();
        public MinHeap(int size)
        {
            items = new List<T>(size);
        }

        public void Add(T item)
        {
            items.Add(item);
            var idx = items.Count - 1;
            var parent = idx >> 1;
            while (idx > 0 && items[idx].CompareTo(items[parent]) < 0)
            {
                T tmp = items[idx];
                items[idx] = items[parent];
                items[parent] = tmp;
                idx = parent;
                parent >>= 1;
            }
        }

        public T RemoveMin()
        {
            if (items.Count == 0) throw new InvalidOperationException();
            var ret = items[0];
            items[0] = items[items.Count - 1];
            items.RemoveAt(items.Count - 1);

            var idx = 0;
            var child = 0;
            while (idx < items.Count)
            {
                var min = idx;
                child = idx << 1;
                if (child + 1 < items.Count && items[child + 1].CompareTo(items[min]) < 0)
                    min = child + 1;
                if (child + 2 < items.Count && items[child + 2].CompareTo(items[min]) < 0)
                    min = child + 2;

                if (min == idx) break;
                var tmp = items[idx];
                items[idx] = items[min];
                items[min] = tmp;
                idx = min;
            }
            return ret;
        }

        public T Peek()
        {
            if (items.Count == 0) throw new InvalidOperationException();
            return items[0];
        }

        public void Clear()
        {
            items.Clear();
        }

        public int Count
        {
            get
            {
                return items.Count;
            }
        }
    }