Created
February 22, 2017 11:59
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// 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; | |
} | |
} | |
} |
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