几种算法的排序和时间

public class Sort {

  public void swap(int a[], int i, int j) {
    int tmp = a[i];
    a[i] = a[j];
    a[j] = tmp;
  }

  public int partition(int a[], int low, int high) {
    int pivot, p_pos, i;
    p_pos = low;
    pivot = a[p_pos];
    for (i = low + 1; i<= high; i++) {
      if (a[i]> pivot) {
        p_pos++;
        swap(a, p_pos, i);
      }
    }
    swap(a, low, p_pos);
    return p_pos;
  }

  public void quicksort(int a[], int low, int high) {
    int pivot;
    if (low< high) {
      pivot = partition(a, low, high);
      quicksort(a, low, pivot - 1);
      quicksort(a, pivot + 1, high);
    }

  }

  public static void main(String args[]) {
    int vec[] = new int[] { 37, 47, 23, -5, 19, 56 };
    int temp;

  
    //选择排序法(Selection Sort)
    long begin = System.currentTimeMillis();
    for (int k = 0; k< 1000000; k++) {
      for (int i = 0; i< vec.length; i++) {
        for (int j = i; j< vec.length; j++) {
          if (vec[j]> vec[i]) {
            temp = vec[i];
            vec[i] = vec[j];
            vec[j] = temp;
          }
        }

      }
    }
    long end = System.currentTimeMillis();
    System.out.println("选择法用时为：" + (end - begin));
    //打印排序好的结果
    for (int i = 0; i< vec.length; i++) {
      System.out.println(vec[i]);
    }

 
    //  冒泡排序法(Bubble Sort)
    begin = System.currentTimeMillis();
    for (int k = 0; k< 1000000; k++) {
      for (int i = 0; i< vec.length; i++) {
        for (int j = i; j< vec.length - 1; j++) {
          if (vec[j + 1]> vec[j]) {
            temp = vec[j + 1];
            vec[j + 1] = vec[j];
            vec[j] = temp;
          }
        }

      }
    }
    end = System.currentTimeMillis();
    System.out.println("冒泡法用时为：" + (end - begin));
    //打印排序好的结果
    for (int i = 0; i< vec.length; i++) {
      System.out.println(vec[i]);
    }

  

    //插入排序法(Insertion Sort)
    begin = System.currentTimeMillis();
    for (int k = 0; k< 1000000; k++) {
      for (int i = 1; i< vec.length; i++) {
        int j = i;
        while (vec[j - 1]< vec[i]) {
          vec[j] = vec[j - 1];
          j--;
          if (j<= 0) {
            break;
          }
        }
        vec[j] = vec[i];
      }
    }
    end = System.currentTimeMillis();
    System.out.println("插入法用时为：" + (end - begin));
    //打印排序好的结果
    for (int i = 0; i< vec.length; i++) {
      System.out.println(vec[i]);
    }

  

    //快速排序法(Quick Sort)

    Sort s = new Sort();
    begin = System.currentTimeMillis();
    for (int k = 0; k< 1000000; k++) {
      s.quicksort(vec, 0, 5);
    }
    end = System.currentTimeMillis();
    System.out.println("快速法用时为：" + (end - begin));
    //打印排序好的结果
    for (int i = 0; i< vec.length; i++) {
      System.out.println(vec[i]);
    }
  }

} 

一直比较厌恶数据结构的排序和估算时间差，今天却捡起800年没再看过的算法重温一遍。不过觉得有点傻气，算法这种东西用什么语言做都好，怎么也轮不到JAVA来实现……呵呵～

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Tags: 算法算法 排序排序
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