forked from ForsFortunaGameDev/suicide-bot-game
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BinaryHeap.cs
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BinaryHeap.cs
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using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using System;
public class BinaryHeap<T> where T : IHeapItem<T> {
T[] items;
int currentItemCount;
public BinaryHeap(int maxHeapSize) {
items = new T[maxHeapSize];
}
public void Add(T item) {
item.HeapIndex = currentItemCount;
items [currentItemCount] = item;
SortUp (item);
currentItemCount++;
}
public T RemoveFirst() {
T firstItem = items [0];
currentItemCount--;
items [0] = items [currentItemCount];
items [0].HeapIndex = 0;
SortDown (items [0]);
return firstItem;
}
public void UpdateItem(T item) {
SortUp (item);
}
public int Count {
get{
return currentItemCount;
}
}
public bool Contains(T item) {
return Equals (items[item.HeapIndex], item);
}
void SortDown(T item) {
while (true) {
int childIndexLeft = item.HeapIndex * 2 + 1;
int childIndexRight = item.HeapIndex * 2 + 2;
int swapIndex = 0;
if (childIndexLeft < currentItemCount) {
swapIndex = childIndexLeft;
if (childIndexRight < currentItemCount) {
if (items [childIndexLeft].CompareTo (items [childIndexRight]) < 0) {
swapIndex = childIndexRight;
}
}
if (item.CompareTo (items [swapIndex]) < 0) {
Swap (item, items[swapIndex]);
} else {
return;
}
} else {
return;
}
}
}
void SortUp(T item) {
int parentIndex = (item.HeapIndex - 1) / 2;
while (true) {
T parentItem = items [parentIndex];
if (item.CompareTo (parentItem) > 0) {
Swap (item, parentItem);
} else {
break;
}
parentIndex = (item.HeapIndex - 1) / 2;
}
}
void Swap(T itemA, T itemB) {
items [itemA.HeapIndex] = itemB;
items [itemB.HeapIndex] = itemA;
int itemAIndex = itemA.HeapIndex;
itemA.HeapIndex = itemB.HeapIndex;
itemB.HeapIndex = itemAIndex;
}
}
public interface IHeapItem<T> : IComparable<T> {
int HeapIndex {
get;
set;
}
}