先从一段代码说起:
package insert;
public class InsertSort {
/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
//int[] array = {2,1, 5, 3, 8,20,7};
//int[] array = {2,1, 5, 3, 8,20,10};
//int[] array = {2,1, 5, 3, 8,20,6};
//int[] array = {2,1, 5, 3, 8, 7,10,23,55,31};
int[] array = {2,1, 5, 3, 8, 7,10,23,55,31,103,102,105,32,32,32,30,30,100,33,32,100,105,107,106,103,102,104};
insertSort(array, array.length);
}
public static void insertSort(int[] array, int len)
{
int i, j, k;
for(i = 0; i < len; i++)
{
int num = -1;
int key = -1;
for( j = 0; j < i; j++)
{
if( array[i] < array[j])
{
num = j;
key = array[i];
break;
}
}
if( num >= 0)
{
int[] temp = new int[i – num];
for( k = num; k < i; k++ )
{
temp[k – num] = array[k];
}
for( k = num; k < i; k++ )
{
array[k + 1] = temp[k – num];
}
array[num] = key;
}
}
for( i = 0; i < len; i++)
{
System.out.println( ” ” + array[i]);
}
}
}
这段程序代码实现了插入排序的功能,也符合人们视线排序算法的常有思路,但是代码冗余度非常大。那么如何改写代码,减少上述代码里面的冗余代码呢?
先看《算法导论》里插入排序的伪代码: