/// <summary>
/// 根据指定数组初始化面向中位数的堆。
/// </summary>
/// <param name="keys">初始数组。</param>
public MedianPq(TKey[] keys)
{
_minPq = new MinPq <TKey>();
_maxPq = new MaxPq <TKey>();
if (keys.Length == 0)
{
_n = 0;
_median = default;
return;
}
_n = keys.Length;
_median = keys[0];
for (var i = 1; i < keys.Length; i++)
{
if (_median.CompareTo(keys[i]) < 0)
{
_minPq.Insert(keys[i]);
}
else
{
_maxPq.Insert(keys[i]);
}
}
UpdateMedian();
}
/// <summary>
/// 构造一个指定容量的面向中位数的堆。
/// </summary>
/// <param name="capacity">初始容量。</param>
public MedianPq(int capacity)
{
_maxPq = new MaxPq <TKey>((capacity - 1) / 2);
_minPq = new MinPq <TKey>((capacity - 1) / 2);
_n = 0;
_median = default;
}
/// <summary>
/// 默认构造函数，构造一个面向中位数的堆。
/// </summary>
public MedianPq()
{
_maxPq = new MaxPq <TKey>();
_minPq = new MinPq <TKey>();
_median = default;
_n = 0;
}
/// <summary>
/// 根据已有元素建立一个最大-最小堆。（O(n)）
/// </summary>
/// <param name="keys">需要建堆的元素。</param>
public MinMaxPq(TKey[] keys)
{
_n = keys.Length;
var minNodes = new MinMaxNode[keys.Length];
var maxNodes = new MinMaxNode[keys.Length];
for (var i = 0; i < _n; i++)
{
MinMaxNode.GetNodes(keys[i], i + 1, out minNodes[i], out maxNodes[i]);
}
_minPq = new MinPq(minNodes);
_maxPq = new MaxPq(maxNodes);
}
/// <summary>
/// 获取堆的迭代器，元素以降序排列。
/// </summary>
/// <returns>最大堆的迭代器。</returns>
public IEnumerator <TKey> GetEnumerator()
{
var copy = new MaxPq <TKey>(N);
for (var i = 1; i <= N; i++)
{
copy.Insert(Pq[i]);
}
while (!copy.IsEmpty())
{
yield return(copy.DelMax()); // 下次迭代的时候从这里继续执行。
}
}
/// <summary>
/// 构造一个指定容量的最大-最小堆。
/// </summary>
/// <param name="capacity">堆的大小。</param>
public MinMaxPq(int capacity)
{
_minPq = new MinPq(capacity);
_maxPq = new MaxPq(capacity);
_n = 0;
}
