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Copy pathHeapSort.java
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53 lines (41 loc) · 1.06 KB
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package sorting;
import java.util.Arrays;
public class HeapSort {
public static void main(String[] args) {
int [] arr = {10, 45, 3, 2, 1, 9, 21, 17};
new HeapSort().doHeapSort(arr);
System.out.println(Arrays.toString(arr));
}
public void doHeapSort(int[] arr) {
heapify(arr, arr.length);
for(int i = 0; i < arr.length - 1; i++) {
//swap the first with the last
int temp = arr[0];
arr[0] = arr[arr.length - i - 1];
arr[arr.length - i - 1] = temp;
heapify(arr, arr.length - i - 1);
}
}
public void heapify(int[] arr, int n) {
for(int i = n/2 - 1; i >= 0; i--) {
maxHeap(i, n, arr);
}
}
public void maxHeap(int i, int n, int[] arr) {
int largest = i;
int left = 2*i + 1;
int right = 2*i + 2;
if(left < n && arr[left] > arr[largest]) {
largest = left;
}
if(right < n && arr[right] > arr[largest]) {
largest = right;
}
if(largest != i) {
int temp = arr[largest];
arr[largest] = arr[i];
arr[i] = temp;
maxHeap(largest, n, arr);
}
}
}