Java 常用排序算法总结
冒泡排序：
/*冒泡算法*/
public class BubbleSort {
public static void bubble_sort(int[] arr){
int temp;
for(int i = 0; i < arr.length - 1;i++){
for(int j = arr.length - 1; j > i; j--){
if(arr[j] < arr[j - 1]){
temp = arr[j];
arr[j] = arr[j -1];
arr[j - 1] = temp;
}
}
show(arr);
}
}
private static void show(int[] arr){
for(int a:arr){
System.out.print(a + " ");
}
System.out.println();
}
public static void main(String[] args){
int[] data = {42,20,17,13,20,14,23,15};
show(data);
System.out.println();
bubble_sort(data);
System.out.println();
show(data);
}
}
输出结果：
42 20 17 13 20 14 23 15
13 42 20 17 14 20 15 23
13 14 42 20 17 15 20 23
13 14 15 42 20 17 20 23
13 14 15 17 42 20 20 23
13 14 15 17 20 42 20 23
13 14 15 17 20 20 42 23
13 14 15 17 20 20 23 42
13 14 15 17 20 20 23 42 选择排序：
/*选择排序算法*/
public class SelectionSort {
public static void selection_sort(int[] arr){
int length = arr.length;
int minIndex;
for(int i = 0; i < length - 1;i++){
minIndex = i;
for(int j = i + 1; j < length; j++){
if(arr[j] < arr[minIndex])
minIndex = j;
}
if(minIndex != i){
int temp = arr[i];
arr[i] = arr[minIndex];
arr[minIndex] = temp;
}
show(arr);
}
}
private static void show(int[] arr){
for(int a:arr){
System.out.print(a + " ");
}
System.out.println();
}
public static void main(String[] args){
int[] data = {42,20,17,13,20,14,23,15};
show(data);
System.out.println();
selection_sort(data);
System.out.println();
show(data);
}
}输出结果：
42 20 17 13 20 14 23 15
13 20 17 42 20 14 23 15
13 14 17 42 20 20 23 15
13 14 15 42 20 20 23 17
13 14 15 17 20 20 23 42
13 14 15 17 20 20 23 42
13 14 15 17 20 20 23 42
13 14 15 17 20 20 23 42
13 14 15 17 20 20 23 42 插入排序：
/*插入算法*/
public class InsertionSort {
public static void insertion_sort(int[] arr){
int temp;
for(int i = 0; i < arr.length - 1; i++){
for(int j = i + 1; j > 0;j--){
if(arr[j] < arr[j-1]){
temp = arr[j-1];
arr[j-1] = arr[j];
arr[j] = temp;
}
else break;
}
show(arr);
}
}
private static void show(int[] arr){
for(int a:arr){
System.out.print(a + " ");
}
System.out.println();
}
public static void main(String[] args){
int[] data = {42,20,17,13,20,14,23,15};
show(data);
System.out.println();
insertion_sort(data);
System.out.println();
show(data);
}
}
输出结果：
42 20 17 13 20 14 23 15
20 42 17 13 20 14 23 15
17 20 42 13 20 14 23 15
13 17 20 42 20 14 23 15
13 17 20 20 42 14 23 15
13 14 17 20 20 42 23 15
13 14 17 20 20 23 42 15
13 14 15 17 20 20 23 42
13 14 15 17 20 20 23 42 希尔排序：
/*希尔排序*/
import java.util.Scanner;
public class ShellSort {
public static void shell_sort(int[] arr, int size){
int temp = 0;
if(arr.length < size){
System.out.println("Sorry, you need to change the size of batch");
}
else {
for(int j = size; j > 0; j--){
for(int i = 0; i + j < arr.length; i++){
if(arr[i + j] < arr[i]) {
temp = arr[i];
arr[i] = arr[i + j];
arr[i + j] = temp;
}
}
show(arr);
}
}
}
private static void show(int[] arr){
for(int a:arr){
System.out.print(a + " ");
}
System.out.println();
}
public static void main(String[] args){
int[] data = {42,20,17,13,20,14,23,15};
show(data);
System.out.println("please enter the size of sort batch");
Scanner in = new Scanner(System.in);
int size = in.nextInt();
System.out.println();
shell_sort(data,size);
System.out.println();
show(data);
}
}
输出结果：
42 20 17 13 20 14 23 15
please enter the size of sort batch
3//符合数组大小要求
13 20 14 23 15 17 42 20
13 20 14 17 15 20 42 23
13 14 17 15 20 20 23 42
13 14 17 15 20 20 23 42
42 20 17 13 20 14 23 15
please enter the size of sort batch
12//超出预定数组大小
Sorry, you need to change the size of batch
42 20 17 13 20 14 23 15 /*快速排列*/
public class QuickSort {
private static void show(int[] arr){
for(int a:arr){
System.out.print(a + " ");
}
System.out.println();
}
public static void quick_sort(int[] arr,int f,int l){
if(f>=l)
return;
int i = f; int j = l; int key = arr[f];//选择第一个数为key
while(i < j){
while(i < j && arr[j] >= key)//从右向左找第一个小于key的值
j--;
if(i < j){
arr[i] = arr[j];
i++;
}
while(i < j && arr[i] < key)//从左向右找第一个大于key的值
i++;
if(i < j){
arr[j] = arr[i];
j--;
}
}
arr[i] = key;
show(arr);
quick_sort(arr, f, i-1);//递归调用
quick_sort(arr, i+1, l);//递归调用
}
public static void main(String[] args){
int[] data = {42,20,17,13,20,14,23,15};
show(data);
System.out.println();
quick_sort(data,0,data.length - 1);
System.out.println();
show(data);
}
}
输出结果：
42 20 17 13 20 14 23 15
15 20 17 13 20 14 23 42
14 13 15 17 20 20 23 42
13 14 15 17 20 20 23 42
13 14 15 17 20 20 23 42
13 14 15 17 20 20 23 42
13 14 15 17 20 20 23 42
13 14 15 17 20 20 23 42 /*归并排序*/
public class MergeSort {
private static void show(int[] arr){
for(int a:arr){
System.out.print(a + " ");
}
System.out.println();
}
public static void merge_sort(int[] arr){
sort(arr,0,arr.length - 1);
}
public static void sort(int[] arr,int left,int right){
if(left >= right)
return;
int center = (left + right) / 2;
sort(arr,left,center);
sort(arr,center + 1,right);
merge(arr,left,center,right);
show(arr);
}
public static void merge(int[] arr,int left,int center,int right){
int[] temparr = new int[arr.length];
int mid = center + 1;
int third = left;
int tmp = left;
while (left <= center && mid <= right){
if(arr[left] <= arr[mid]){
temparr[third++] = arr[left++];
}
else
temparr[third++] = arr[mid++];
}
while (mid <= right){
temparr[third++] = arr[mid++];
}
while (left <= center){
temparr[third++] = arr[left++];
}
while (tmp <= right){
arr[tmp] = temparr[tmp++];
}
}
public static void main(String[] args){
int[] data = {42,20,17,13,20,14,23,15};
show(data);
System.out.println();
merge_sort(data);
System.out.println();
show(data);
}
}
输出结果：
42 20 17 13 20 14 23 15
20 42 17 13 20 14 23 15
20 42 13 17 20 14 23 15
13 17 20 42 20 14 23 15
13 17 20 42 14 20 23 15
13 17 20 42 14 20 15 23
13 17 20 42 14 15 20 23
13 14 15 17 20 20 23 42
13 14 15 17 20 20 23 42