Question

http://pt.wikipedia.org/wiki/Merge_sort#Java
That code does not compile.

Thank you.

Answer 1

Here’s a working implementation from http://rosettacode.org/wiki/Merge_sort#Java, linked to from the English Wikipedia article on merge sort.

import java.util.LinkedList;  
public class Merge<E extends Comparable<? super E>> {  
    public LinkedList<E> mergeSort(LinkedList<E> m){  
        if(m.size() <= 1) return m;  

        int middle= m.size() / 2;  
        LinkedList<E> left= new LinkedList<E>();  
        for(int i= 0;i < middle;i++) left.add(m.get(i));  
        LinkedList<E> right= new LinkedList<E>();  
        for(int i= middle;i < m.size();i++) right.add(m.get(i));  

        right= mergeSort(right);  
        left= mergeSort(left);  
        LinkedList<E> result= merge(left, right);  

        return result;  
    }  

    public LinkedList<E> merge(LinkedList<E> left, LinkedList<E> right){  
        LinkedList<E> result= new LinkedList<E>();  

        while(!left.isEmpty() && !right.isEmpty()){  
            //change the direction of this comparison to change the direction of the sort  
            if(left.peek().compareTo(right.peek()) <= 0) result.add(left.remove());  
            else result.add(right.remove());  
        }  

        result.addAll(left);  
        result.addAll(right);  
        return result;  
    }  
}