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HeapSort.java
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HeapSort.java
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/**
* Copyright © https://github.com/jarry All rights reserved.
* @author: [email protected]
* @version: 1.0
*/
import java.util.Arrays;
public class HeapSort {
private static int getLeft(int i) {
return i * 2 + 1;
}
private static int getRight(int i) {
return i * 2 + 2;
}
static void swap(int arr[], int from, int to) {
int temp = arr[from];
arr[from] = arr[to];
arr[to] = temp;
}
private static void maxHeapify(int arr[], int idx, int size) {
int max = idx;
int left = getLeft(idx);
int right = getRight(idx);
if (left < size && arr[left] > arr[max]) {
max = left;
}
if (right < size && arr[right] > arr[max]) {
max = right;
}
System.out.println("idx=" + idx + " left=" + left + " right=" + right + " max=" + max + " size=" + size);
if (max != idx) {
swap(arr, idx, max);
maxHeapify(arr, max, size);
}
}
static void heapSort(int arr[]) {
int len = arr.length;
int parent = (len - 1) / 2 - 1;
int child = len - 1;
while (parent >= 0) {
maxHeapify(arr, parent, len);
System.out.println("parent sort:" + parent + " " + len + " ");
parent--;
}
System.out.println("child start: parent=" + parent + " child=" + child);
while (child > 0) {
swap(arr, 0, child);
maxHeapify(arr, 0, child);
System.out.println("child sort:" + 0 + " " + child + " ");
child--;
}
}
public static void main(String[] args) {
int arr[] = { 7, 11, 9, 10, 12, 13, 8 };
System.out.println("sort start:" + Arrays.toString(arr));
long startTime = System.currentTimeMillis();
HeapSort.heapSort(arr);
System.out.println("\r\ntime:" + (System.currentTimeMillis() - startTime) + " ms.");
System.out.println("sorted:" + Arrays.toString(arr));
}
}
/*
oringal array: [7, 11, 9, 10, 12, 13, 8]
heap:
7(0)
/ \
11(1) 9(2)
/ \ / \
10(3) 12(4) 13(5) 8(6)
父节点步骤
1. maxHeapify: idx= 2 left= 5 right= 6 max= 5 size= 7
7(0)
/ \
11(1) 13(2)
/ \ / \
10(3) 12(4) 9(5) 8(6)
2. maxHeapify: idx= 1 left= 3 right= 4 max= 4 size= 7
7(0)
/ \
12(1) 13(2)
/ \ / \
10(3) 11(4) 9(5) 8(6)
3. maxHeapify: idx= 0 left= 1 right= 2 max= 2 size= 7
13(0)
/ \
12(1) 7(2)
/ \ / \
10(3) 11(4) 9(5) 8(6)
3.1 maxHeapify recursion: idx= 2 left= 5 right= 6 max= 5 size= 7
13(0)
/ \
12(1) 9(2)
/ \ / \
10(3) 11(4) 7(5) 8(6)
子节点堆排序:
1. swap, child = 6:
8(0)
/ \
12(1) 9(2)
/ \ / \
10(3) 11(4) 7(5) 13(6)
1.1 maxHeapify: idx= 0 left= 1 right= 2 max= 1 size= 6
12(0)
/ \
8(1) 9(2)
/ \ / \
10(3) 11(4) 7(5) 13(6)
1.2 maxHeapify recursion: idx= 1 left= 3 right= 4 max= 4 size= 6
12(0)
/ \
11(1) 9(2)
/ \ / \
10(3) 8(4) 7(5) 13(6)
2. swap, child = 5:
7(0)
/ \
11(1) 9(2)
/ \ / \
10(3) 8(4) 12(5) 13(6)
2.1 maxHeapify: idx= 0 left= 1 right= 2 max= 1 size= 5
11(0)
/ \
7(1) 9(2)
/ \ / \
10(3) 8(4) 12(5) 13(6)
2.2 maxHeapify recursion: idx= 1 left= 3 right= 4 max= 3 size= 5
11(0)
/ \
10(1) 9(2)
/ \ / \
7(3) 8(4) 12(5) 13(6)
3. swap, child = 4:
8(0)
/ \
10(1) 9(2)
/ \ / \
7(3) 11(4) 12(5) 13(6)
3.1 maxHeapify: idx= 0 left= 1 right= 2 max= 1 size= 4
10(0)
/ \
8(1) 9(2)
/ \ / \
7(3) 11(4) 12(5) 13(6)
3.2 maxHeapify recursion: idx= 1 left= 3 right= 4 max= 1 size= 4
4. swap, child = 3:
7(0)
/ \
8(1) 9(2)
/ \ / \
10(3) 11(4) 12(5) 13(6)
4.1 maxHeapify: idx= 0 left= 1 right= 2 max= 2 size= 3
9(0)
/ \
8(1) 7(2)
/ \ / \
10(3) 11(4) 12(5) 13(6)
4.2 maxHeapify recursion: idx= 2 left= 5 right= 6 max= 2 size= 3
5. swap, child = 2:
7(0)
/ \
8(1) 9(2)
/ \ / \
10(3) 11(4) 12(5) 13(6)
5.1 maxHeapify: idx= 0 left= 1 right= 2 max= 1 size= 2
8(0)
/ \
7(1) 9(2)
/ \ / \
10(3) 11(4) 12(5) 13(6)
5.2 maxHeapify recursion: idx= 1 left= 3 right= 4 max= 1 size= 2
6. swap, child = 1:
7(0)
/ \
8(1) 9(2)
/ \ / \
10(3) 11(4) 12(5) 13(6)
6.1 maxHeapify: idx= 0 left= 1 right= 2 max= 0 size= 1
*/
/**
jarrys-MacBook-Pro:heapsort jarry$ javac HeapSort.java
jarrys-MacBook-Pro:heapsort jarry$ java HeapSort
sort start:[7, 11, 9, 10, 12, 13, 8]
idx=2 left=5 right=6 max=5 size=7
idx=5 left=11 right=12 max=5 size=7
parent sort:2 7
idx=1 left=3 right=4 max=4 size=7
idx=4 left=9 right=10 max=4 size=7
parent sort:1 7
idx=0 left=1 right=2 max=2 size=7
idx=2 left=5 right=6 max=5 size=7
idx=5 left=11 right=12 max=5 size=7
parent sort:0 7
child start: parent=-1 child=6
idx=0 left=1 right=2 max=1 size=6
idx=1 left=3 right=4 max=4 size=6
idx=4 left=9 right=10 max=4 size=6
child sort:0 6
idx=0 left=1 right=2 max=1 size=5
idx=1 left=3 right=4 max=3 size=5
idx=3 left=7 right=8 max=3 size=5
child sort:0 5
idx=0 left=1 right=2 max=1 size=4
idx=1 left=3 right=4 max=1 size=4
child sort:0 4
idx=0 left=1 right=2 max=2 size=3
idx=2 left=5 right=6 max=2 size=3
child sort:0 3
idx=0 left=1 right=2 max=1 size=2
idx=1 left=3 right=4 max=1 size=2
child sort:0 2
idx=0 left=1 right=2 max=0 size=1
child sort:0 1
time:55 ms.
sorted:[7, 8, 9, 10, 11, 12, 13]
*/