Priority Queue for C#

PriorityQueue.cs

// Copyright (c) 2020 Kazuhiro Fujieda
//
// Permission to use, copy, modify, and/or distribute this software for any
// purpose with or without fee is hereby granted.
//
// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
// REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
// AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
// INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
// LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
// OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
// PERFORMANCE OF THIS SOFTWARE.

using System;
using System.Collections.Generic;

public class PriorityQueue<T> where T : IComparable<T>
{
    private readonly List<T> _array = new List<T>();

    private readonly int _order;

    public PriorityQueue(bool min = false)
    {
        _order = min ? -1 : 1;
    }

    public int Count => _array.Count;

    public void Push(T item)
    {
        var child = _array.Count;
        _array.Add(item);
        while (child > 0)
        {
            var parent = (child - 1) / 2;
            if (_order * _array[child].CompareTo(_array[parent]) > 0)
                Swap(child, parent);
            child = parent;
        }
    }

    public T Pop()
    {
        var last = _array.Count - 1;
        var r = _array[0];
        _array[0] = _array[last];
        _array.RemoveAt(last);
        last--;
        for (int child = 1, parent = 0; child <= last; child = 2 * parent + 1)
        {
            var left = child;
            var right = child + 1;
            if (right <= last && _order * _array[right].CompareTo(_array[left]) > 0)
                child = right;
            if (_order * _array[child].CompareTo(_array[parent]) > 0)
                Swap(parent, child);
            parent = child;
        }
        return r;
    }

    private void Swap(int i, int j)
    {
        var tmp = _array[j];
        _array[j] = _array[i];
        _array[i] = tmp;
    }
}