package com.smile.test.sort.bubble;
/**
* 冒泡排序 时间复杂度O(n^2)
*/
public class Bubble {
static void sort(Comparable[] a){
for (int i = a.length-1; i>0; i--){
for (int j=0; j<i; j++){
if(greater(a[j],a[j+1])){
changeIndex(a, j, j+1);
}
}
}
}
private static boolean greater(Comparable a,Comparable b){
return a.compareTo(b) > 0;
}
private static void changeIndex(Comparable[] a,int i,int j){
Comparable temp;
temp = a[i];
a[i] = a[j];
a[j] = temp;
}
}
import java.util.Arrays;
public class BubbleTest {
public static void main(String[] args) {
Integer[] a = {6,5,4,3,2,1};
Bubble.sort(a);
System.out.println(Arrays.toString(a));
}
}
[1, 2, 3, 4, 5, 6]
Process finished with exit code 0
选择排序
public class Selections {
static void sort(Comparable[] a){
for (int i = 0; i <= a.length - 2; i++){
int minIndex = i;
for (int j = i+1; j < a.length; j++){
if (greater(a[minIndex], a[j])){
minIndex = j;
}
}
changeIndex(a, minIndex,i);
}
}
// 比较a,b的大小
private static boolean greater(Comparable a,Comparable b){
return a.compareTo(b) > 0;
}
// 交换索引i 和 索引j处的值
private static void changeIndex(Comparable[] a,int i,int j){
Comparable temp;
temp = a[i];
a[i] = a[j];
a[j] = temp;
}
}
import java.util.Arrays;
public class SelectionsTest {
public static void main(String[] args) {
Integer[] arr = {4,5,8,9,6,3,1};
Selections.sort(arr);
System.out.println(Arrays.toString(arr));
}
}
[1, 3, 4, 5, 6, 8, 9]
Process finished with exit code 0
插入排序
public class InsertSort {
public static void sort(Comparable[] a){
for (int i = 1; i < a.length; i++){
for(int j = i; j>0; j--){
if (greater(a[j-1], a[j])){
changeIndex(a,j-1,j);
}
}
}
}
// 比较a,b的大小
private static boolean greater(Comparable a,Comparable b){
return a.compareTo(b) > 0;
}
// 交换索引i 和 索引j处的值
private static void changeIndex(Comparable[] a,int i,int j){
Comparable temp;
temp = a[i];
a[i] = a[j];
a[j] = temp;
}
}
import java.util.Arrays;
public class InsertTest {
public static void main(String[] args) {
Integer[] a = {4,3,2,10,12,1,5,6};
InsertSort.sort(a);
System.out.println(Arrays.toString(a));
}
}
[1, 2, 3, 4, 5, 6, 10, 12]
Process finished with exit code 0