快速排序

快速排序的思想依据是分治法，选取第一个元素为对比值，然后将表中比对比值小的放在左边，将对比值大的放在右边，然后再将左边的列表用同样的方法进行排列，将右边的方法进行排列，依次递归下去，最终有序。下面列出java实现

package arithmetic;

/**

* Created by elijahliu on 2017/3/2.

*/

public class QuickSort {

int a[] = {49,37,65,97,76,13,27,49,78};

public QuickSort(){

quickSort(a,0,a.length-1);

for (int i:a

) {

System.out.print(i+" ");

}

}

public int getMiddle(int[] list,int low,int high){

int temp = list[low];

while (low < high) {

while (low < high && list[high] >= temp) {

high--;

}

list[low] = list[high];

while (low < high && list[low] <= temp) {

low++;

}

list[high] = list[low];

}

list[low] = temp;

return low;

}

public void _quickSort(int[] list, int low, int high) {

if (low < high) {

int mid = getMiddle(list, low, high);

_quickSort(list, low, mid - 1);

_quickSort(list, mid + 1, high);

}

}

public void quickSort(int[] list, int low, int high) {

if (list.length > 0) {

_quickSort(list, low, high);

}

}

public static void main(String[] args) {

new QuickSort();

}

}

直接插入排序

直接插入排序的算法思想：从第二个元素开始，如果比前面的元素都小，那么就将前面的元素往后移一位，然后把自己的值放到前面的位置上，最终由小到大排列。

java实现

package arithmetic;

/**

* Created by elijahliu on 2017/3/2.

*/

public class InsertSort {

public InsertSort(){

insertSort();

}

int a[] = {49, 38, 65, 97, 76, 13, 27, 49};

public void insertSort(){

int temp = 0;

for(int i = 1;i

temp = a[i];

int j = i - 1;

for(;j>=0&&temp

a[j + 1] = a[j];

}

a[j + 1] = temp;

}

for (int i:a

) {

System.out.println(i+" ");

}

}

public static void main(String[] args) {

new InsertSort();

}

}

冒泡排序

最简单的冒泡排序，大一就学过了

package arithmetic;

/**

* Created by elijahliu on 2017/3/2.

*/

public class BubbleSort {

public BubbleSort() {

bubbleSort();

}

int a[] = {49, 38, 65, 97, 76, 13};

public void bubbleSort() {

int temp = 0;

for (int i = 0; i < a.length - 1; i++) {

for (int j = 0; j < a.length - 1 - i; j++) {

if (a[j] > a[j + 1]) {

temp = a[j];

a[j] = a[j + 1];

a[j + 1] = temp;

}

}

}

for (int i : a

) {

System.out.println(i + "");

}

}

public static void main(String[] args) {

new BubbleSort();

}

}

简单选择排序

算法思想：选取第一个作为标准值，然后对比后面的数，选取一个最大的，与第一个进行交换，position用于标记最大的数的位置。然后选择第二个数为标准值，然后依次进行下去。

package arithmetic;

/**

* Created by elijahliu on 2017/3/2.

*/

public class SelectSort {

int a[] = {1, 54, 6, 3, 78, 34, 12, 45};

public SelectSort() {

seletctSort();

}

public void seletctSort() {

int position = 0;

for (int i = 0; i < a.length; i++) {

position = i;

int temp = a[i];

for (int j = i + 1; j < a.length; j++) {

if (a[j] > temp) {

temp = a[j];

position = j;

}

}

a[position] = a[i];

a[i] = temp;

}

for (int i : a

) {

System.out.print(i + " ");

}

}

public static void main(String[] args) {

new SelectSort();

}

}