public class BubbleSort { 
  public static void main(String[] args) { 
    int len = 10; 
    int[] ary = new int[len]; 
    Random random = new Random(); 
    for (int j = 0; j < len; j++) { 
      ary[j] = random.nextInt(1000); 
    } 
   
    System.out.println("-------排序前------"); 
    for (int j = 0; j < ary.length; j++) { 
      System.out.print(ary[j] + " "); 
    } 
    /* 
     * 升序， Asc1和Asc2优化了内部循环的比较次数，比较好 
     * 总的比较次数： 
     *   Asc1、Asc2：(1+n-1)/2*(n-1) ==> n/2*(n-1) ==> n*(n-1)/2 ==>(n^2-n)/2 
     *   Asc： n^2-n 
     */ 
//   orderAsc(ary); 
//   orderAsc2(ary); 
    orderAsc1(ary); 
     
    //降序，只需要把判断大小于 置换一下 
     
  } 
   
  static void orderAsc(int[] ary) { 
    int count = 0;//比较次数 
    int len = ary.length; 
    for (int j = 0; j < len; j++) {//外层固定循环次数 
      for (int k = 0; k < len - 1; k++) {//内层固定循环次数 
        if (ary[k] > ary[k + 1]) { 
          ary[k] = ary[k + 1] + (ary[k + 1] = ary[k]) * 0;//一步交换 
          /* 交换两个变量值 
           * a=a+b 
           * b=a-b 
           * a=a-b 
           */ 
        }  
        count++; 
      } 
    } 
    System.out.println("\n-----orderAsc升序排序后------次数：" + count); 
    for (int j = 0; j < len; j++) { 
      System.out.print(ary[j] + " "); 
    } 
  } 
   
  static void orderAsc1(int[] ary) { 
    int count = 0;//比较次数 
    int len = ary.length; 
    for (int j = 0; j < len; j++) {//外层固定循环次数 
      for (int k = len - 1; k > j; k--) {//内层从多到少递减比较次数 
        if (ary[k] < ary[k - 1]) { 
          ary[k] = ary[k - 1] + (ary[k - 1] = ary[k]) * 0;//一步交换 
        }  
        count++; 
      } 
    } 
    System.out.println("\n-----orderAsc1升序排序后------次数：" + count); 
    for (int j = 0; j < len; j++) { 
      System.out.print(ary[j] + " "); 
    } 
  } 
 
  static void orderAsc2(int[] ary) { 
    int count = 0;//比较次数 
    int len = ary.length; 
    for (int j = len - 1; j > 0; j--) {//外层固定循环次数 
      /* 
       * k < j; 总的比较次数=(n^2-n)/2 
       */ 
      for (int k = 0; k < j; k++) {//内层从多到少递减比较次数 
        if (ary[k] > ary[k + 1]) { 
          ary[k] = ary[k + 1] + (ary[k + 1] = ary[k]) * 0;//一步交换 
        } 
        count++; 
      } 
    } 
    System.out.println("\n-----orderAsc2升序排序后------次数：" + count); 
    for (int j = 0; j < len; j++) { 
      System.out.print(ary[j] + " "); 
    } 
  } 
} 

-------排序前------ 
898 7 862 286 879 660 433 724 316 737  
-----orderAsc1升序排序后------次数：45 
7 286 316 433 660 724 737 862 879 898  

public class Bubble_CocktailSort { 
  public static void main(String[] args) { 
    int len = 10; 
    int[] ary = new int[len]; 
    Random random = new Random(); 
    for (int j = 0; j < len; j++) { 
      ary[j] = random.nextInt(1000); 
    } 
    /* 
     * 交换次数最小也是1次，最大也是(n^2-n)/2次 
     */ 
//   ary=new int[]{10,9,8,7,6,5,4,3,2,1}; //测试交换次数 
//   ary=new int[]{1,2,3,4,5,6,7,8,10,9}; //测试交换次数 
    System.out.println("-------排序前------"); 
    for (int j = 0; j < ary.length; j++) { 
      System.out.print(ary[j] + " "); 
    } 
     
    orderAsc1(ary); 
//   orderAsc2(ary); 
     
    //降序，只需要把判断大小于 置换一下 
     
  } 
   
  static void orderAsc1(int[] ary) { 
    int compareCount = 0;//比较次数 
    int changeCount = 0;//交换次数 
    int len = ary.length; 
    int left = 0, right = len -1, tl, tr; 
    while (left < right) {//外层固定循环次数 
      tl = left + 1; 
      tr = right - 1; 
      for (int k = left; k < right; k++) {//内层从多到少递减比较次数, 从左向右 
        if (ary[k] > ary[k + 1]) {//前大于后， 置换 
          ary[k] = ary[k + 1] + (ary[k + 1] = ary[k]) * 0;//一步交换 
          changeCount++; 
          tr = k; //一轮中最后一比较的时候，将k所在索引赋给tr, tr表示以后比较的结束索引值, 从左向右比后，k表示左边的索引 
        }  
        compareCount++; 
      } 
      right = tr; 
      for (int k = right; k > left; k--) {//内层从多到少递减比较次数, 从右向左 
        if (ary[k] < ary[k - 1]) {//后小于前 置换 
          ary[k] = ary[k - 1] + (ary[k - 1] = ary[k]) * 0;//一步交换 
          changeCount++; 
          tl = k; //一轮中最后一比较的时候，将k所在索引赋给tl, tl表示以后比较的开始索引值, 从向右向左比后，k表示右边的索引 
        }  
        compareCount++; 
      } 
      left = tl; 
    } 
    System.out.println("\n-----orderAsc1升序排序后------比较次数：" + compareCount + ", 交换次数：" + changeCount); 
    for (int j = 0; j < len; j++) { 
      System.out.print(ary[j] + " "); 
    } 
  } 
   
  //跟orderAsc1的思路没有区别 
  static void orderAsc2(int[] ary) { 
    int compareCount = 0;//比较次数 
    int changeCount = 0;//交换次数 
    int len = ary.length; 
    int l = 0, r = len -1, tl, tr; 
    for (; l < r; ) {//外层固定循环次数 
      tl = l + 1; 
      tr = r - 1; 
      /* 
       * 从左向右比，将大的移到后面 
       */ 
      for (int k = l; k < r; k++) { 
        if (ary[k] > ary[k + 1]) { 
          int temp = ary[k] + ary[k + 1]; 
          ary[k + 1] = temp - ary[k + 1]; 
          ary[k] = temp - ary[k + 1]; 
          changeCount++; 
          tr = k; 
        } 
        compareCount++; 
      } 
      r = tr; 
      /* 
       * 从右向左比，将小的移到前面 
       */ 
      for (int k = r; k > l; k--) { 
        if (ary[k] < ary[k - 1]) { 
          int temp = ary[k] + ary[k - 1]; 
          ary[k - 1] = temp - ary[k - 1]; 
          ary[k] = temp - ary[k - 1]; 
          changeCount++; 
          tl = k; 
        } 
        compareCount++; 
      } 
      l = tl; 
    } 
    System.out.println("\n-----orderAsc2升序排序后------比较次数：" + compareCount + ", 交换次数：" + changeCount); 
    for (int j = 0; j < len; j++) { 
      System.out.print(ary[j] + " "); 
    } 
  } 
} 

-------排序前------ 
783 173 53 955 697 839 201 899 680 677  
-----orderAsc1升序排序后------比较次数：34, 交换次数：22 
53 173 201 677 680 697 783 839 899 955