排序算法
1.插入排序
public void insertArray(Integer[] in ) {
int tem =0;
int num =0;
int upnum =0;
for (int i =0; i < in .length; i++) {
for (int j = i -1; j >=0; j--) {
num++;
if ( in [j +1] < in [j]) {
tem = in [j +1]; in [j +1] = in [j]; in [j] = tem;
upnum++;
}else {
break;
}
}
}
for (int i =0; i < in .length; i++) {
System.out.print( in [i]);
if (i < in .length -1) {
System.out.print(",");
}
}
System.out.println();
System.out.println("插入排序循环次数:" + num);
System.out.println("移动次数：" + upnum);
System.out.print("\n\n\n");
}
比较两个值的大小，如果后边的值比前边的值小，将后边的值与前边的值互换，如果后边的值比前边的值大，就继续比较后边的两个值
2.选择排序
//选择排序
public void chooseArray(Integer[] in ) {
int tem =0;
int num =0;
int upnum =0;
for (int i =0; i < in .length; i++) {
for (int j =0; j < in .length -1; j++) {
num++;
if ( in [j +1] < in [j]) {
tem = in [j +1]; in [j +1] = in [j]; in [j] = tem;
upnum++;
}
}
}
for (int i =0; i < in .length; i++) {
System.out.print( in [i]);
if (i < in .length -1) {
System.out.print(",");
}
}
System.out.println();
System.out.println("选择排序循环次数:" + num);
System.out.println("移动次数：" + upnum);
System.out.print("\n\n\n");
}
循环将小的值放到前边
3.冒泡排序
//冒泡排序
public void efferArray(Integer[] in ) {
int tem =0;
int num =0;
int upnum =0;
for (int i =0; i < in .length; i++) {
for (int j = i; j < in .length -1; j++) {
num++;
if ( in [j +1] < in [i]) {
tem = in [j +1]; in [j +1] = in [i]; in [i] = tem;
upnum++;
}
}
}
for (int i =0; i < in .length; i++) {
System.out.print( in [i]);
if (i < in .length -1) {
System.out.print(",");
}
}
System.out.println();
System.out.println("冒泡排序循环次数:" + num);
System.out.println("移动次数：" + upnum);
System.out.print("\n\n\n");
}
冒泡排序是选择排序的升级版，能够一定限度的减少循环的次数
总结
选择排序是最原始的排序算法，运行结果不稳定，作为了解就行，循环次数为n*n次
插入排序是选择排序的改良版，利用break减少了循环的次数，运行结果稳定，循环次数为n*n~n次比较，n*n~1次插入
冒泡排序是插入排序的改良版，同时也牺牲了运行开销，运行结果稳定，循环次数为n*n~n次
快速排序是冒泡排序的升级版，但是运行结果不是很稳定，循环次数为n*n~n*log n次
归并排序(合并排序)是现在应用最广的排序算法，java1.7后Collections.sort使用的默认排序就是归并排序，运用化整为零的思想，将源集合分成若干小集合最好合并结果，运行结果稳定，循环次数为n*log n次
数学知识补充log n意思是2的几次方等于n，例如log 1=0,log 2=1,log 4=2,log 8=3
当然，还有希尔排序，堆排序在这里就不多说了
参考:https://www.cs.usfca.edu/~galles/visualization/Algorithms.html
