InsertionSort.java

package sorts;

import java.util.Comparator;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * InsertionSort.java
 * Created by Stijn Strickx on May 21, 2008
 * Copyright 2008 Stijn Strickx, All rights reserved
 */

/**
 * Insertion sort algorithm
 * Time Complexity: O(n*n)
 * Memory Complexity: O(1)
 * Stable: yes
 */

public class InsertionSort extends Sorter{
    private static Log log = LogFactory.getFactory().getInstance(
    		InsertionSort.class);

    @Override
    public <T extends Comparable<? super T>> void sort(T[] a) {
        for(int i = 1; i < a.length; i++){
            int j = i;
            T o = a[i];
            while((j > 0) && o.compareTo(a[j-1]) < 0){
                a[j] = a[j-1];
                j--;
            }
            a[j] = o;
        }
    }
    
    public <T> void sort(T[] a, Comparator<T> c) {
        for(int i = 1; i < a.length; i++){
            int j = i;
            T o = a[i];
            while((j > 0) && c.compare(o, a[j-1]) < 0){
            	if (log.isDebugEnabled())
            		log.debug("swapping (" + String.valueOf(j) + ") " + a[j].toString() 
            			+ " for (" + String.valueOf(j-1) + ") " + a[j-1].toString());
                a[j] = a[j-1];
                j--;
            }
            a[j] = o;
        }
    }
}