Created
March 23, 2019 18:50
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HeapSort implementation java
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| package nauka; | |
| import java.util.Random; | |
| public class HeapSort { | |
| private static int heapSize; | |
| private static int right(int index) { | |
| return (index << 1) + 2; | |
| } | |
| private static int left(int index) { | |
| return (index << 1) + 1; | |
| } | |
| private static final void swap(int index1, int index2, int[] arr) { | |
| int temp = arr[index1]; | |
| arr[index1] = arr[index2]; | |
| arr[index2] = temp; | |
| } | |
| private static void heapify(int[] arr, int index) { | |
| int left = left(index); | |
| int right = right(index); | |
| int largest; | |
| if (left < heapSize && arr[left] > arr[index]) | |
| largest = left; | |
| else | |
| largest = index; | |
| if (right < heapSize && arr[right] > arr[largest]) | |
| largest = right; | |
| if (largest != index) { | |
| swap(largest,index,arr); | |
| heapify(arr,largest); | |
| } | |
| } | |
| private static void buildMaxHeap(int[] arr) { | |
| heapSize = arr.length; | |
| for(int i=(arr.length-1)/2;i>=0;i--) heapify(arr, i); | |
| } | |
| static void heapSort(int[] arr) { | |
| buildMaxHeap(arr); | |
| for(int i=arr.length-1;i>0;i--) { | |
| swap(i,0,arr); | |
| heapSize--; | |
| heapify(arr,0); | |
| } | |
| } | |
| public static void main(String[] args) { | |
| Random r = new Random(); | |
| int[] arr = r.ints(0,50).limit(20).toArray(); | |
| for(int n:arr) System.out.printf("%d ",n); | |
| System.out.println(); | |
| heapSort(arr); | |
| for(int n:arr) System.out.printf("%d ",n); | |
| } | |
| } |
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