Java直接插入排序算法實現

2019-11-26 15:48:45

字體：大中小

來源：轉載

供稿：網友

序：一個愛上Java最初的想法一直沒有磨滅：”分享我的學習成果，不管后期技術有多深，打好基礎很重要“。

工具類Swapper，后期算法會使用這個工具類：

package com.meritit.sortord.util;

/**
* One util to swap tow element of Array
*
* @author ysjian
* @version 1.0
* @email ysjian_pingcx@126.com
* @QQ 646633781
* @telephone 18192235667
* @csdnBlog http://blog.csdn.net/ysjian_pingcx
* @createTime 2013-12-20
* @copyRight Merit
*/
public class Swapper {

private Swapper() {

}

/**
* Swap tow elements of the array
*
* @param oneIndex
*            one index
* @param anotherIndex
*            another index
* @param array
*            the array to be swapped
* @exception NullPointerException
*                if the array is null
*/
public static <T extends Comparable<T>> void swap(int oneIndex,
   int anotherIndex, T[] array) {
  if (array == null) {
   throw new NullPointerException("null value input");
  }
  checkIndexs(oneIndex, anotherIndex, array.length);
  T temp = array[oneIndex];
  array[oneIndex] = array[anotherIndex];
  array[anotherIndex] = temp;
}

/**
* Swap tow elements of the array
*
* @param oneIndex
*            one index
* @param anotherIndex
*            another index
* @param array
*            the array to be swapped
* @exception NullPointerException
*                if the array is null
*/
public static void swap(int oneIndex, int anotherIndex, int[] array) {
  if (array == null) {
   throw new NullPointerException("null value input");
  }
  checkIndexs(oneIndex, anotherIndex, array.length);
  int temp = array[oneIndex];
  array[oneIndex] = array[anotherIndex];
  array[anotherIndex] = temp;
}

/**
* Check the index whether it is in the arrange
*
* @param oneIndex
*            one index
* @param anotherIndex
*            another index
* @param arrayLength
*            the length of the Array
* @exception IllegalArgumentException
*                if the index is out of the range
*/
private static void checkIndexs(int oneIndex, int anotherIndex,
   int arrayLength) {
  if (oneIndex < 0 || anotherIndex < 0 || oneIndex >= arrayLength
    || anotherIndex >= arrayLength) {
   throw new IllegalArgumentException(
     "illegalArguments for tow indexs [" + oneIndex + ","
       + oneIndex + "]");
  }
}
}

直接插入排序，InsertionSortord：

復制代碼代碼如下:

package com.meritit.sortord.insertion;

/**
* Insertion sort order, time complexity is O(n2)
*
* @author ysjian
* @version 1.0
* @email ysjian_pingcx@126.com
* @QQ 646633781
* @telephone 18192235667
* @csdnBlog http://blog.csdn.net/ysjian_pingcx
* @createTime 2013-12-31
* @copyRight Merit
* @since 1.5
*/
public class InsertionSortord {

private static final InsertionSortord INSTANCE = new InsertionSortord();

private InsertionSortord() {
}

/**
* Get the instance of InsertionSortord, only just one instance
*
* @return the only instance
*/
public static InsertionSortord getInstance() {
return INSTANCE;
}

/**
* Sort the array of <code>int</code> with insertion sort order
*
* @param array
*            the array of int
*/
public void doSort(int... array) {
  if (array != null && array.length > 0) {
   int length = array.length;

   // the circulation begin at 1,the value of index 0 is reference
   for (int i = 1; i < length; i++) {
    if (array[i] < array[i - 1]) {

// if value at index i is lower than the value at index i-1
int vacancy = i; // record the vacancy as i

// set a sentry as the value at index i
int sentry = array[i];

     // key circulation ,from index i-1 ,
     for (int j = i - 1; j >= 0; j--) {
      if (array[j] > sentry) {
       /*
        * if the current index value exceeds the
        * sentry,then move backwards, set record the new
        * vacancy as j
        */
       array[j + 1] = array[j];
       vacancy = j;
      }
     }
     // set the sentry to the new vacancy
     array[vacancy] = sentry;
    }
   }
  }
}

/**
* Sort the array of generic <code>T</code> with insertion sort order
*
* @param array
*            the array of generic
*/
public <T extends Comparable<T>> void doSortT(T[] array) {
  if (array != null && array.length > 0) {
   int length = array.length;
   for (int i = 1; i < length; i++) {
    if (array[i].compareTo(array[i - 1]) < 0) {
     T sentry = array[i];
     int vacancy = i;
     for (int j = i - 1; j >= 0; j--) {
      if (array[j].compareTo(sentry) > 0) {
       array[j + 1] = array[j];
       vacancy = j;
      }

     }
     array[vacancy] = sentry;
    }
   }
  }
}
}

測試TestInsertionSortord：

復制代碼代碼如下:

package com.meritit.sortord.insertion;

import java.util.Arrays;

/**
* Test insertion sort order
*
* @author ysjian
* @version 1.0
* @email ysjian_pingcx@126.com
* @QQ 646633781
* @telephone 18192235667
* @createTime 2013-12-31
* @copyRight Merit
*/
public class TestInsertionSortord {

public static void main(String[] args) {
  InsertionSortord insertSort = InsertionSortord.getInstance();
  int[] array = { 3, 5, 4, 2, 6 };
  System.out.println(Arrays.toString(array));
  insertSort.doSort(array);
  System.out.println(Arrays.toString(array));
  System.out.println("---------------");
  Integer[] array1 = { 3, 5, 4, 2, 6 };
  System.out.println(Arrays.toString(array1));
  insertSort.doSortT(array1);
  System.out.println(Arrays.toString(array1));
}
}