归并排序

package sort;

public class MergeSort {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        
        int[] arr={16,7,3,20,17,8};
        
        int[] result=mergeSort(arr);
        
        for(int i=0; i<result.length; i++)
            System.out.print(result[i]+" ");
    }

    private static int[] mergeSort(int[] arr) {
        // TODO Auto-generated method stub
        
        if(arr.length==1)
            return arr;
        
        int half=arr.length/2;
        int[] a=new int[half];
        int[] b=new int[arr.length-half];
        
        System.arraycopy(arr, 0, a, 0, half);
        System.arraycopy(arr, half, b, 0, b.length);
        a=mergeSort(a);
        b=mergeSort(b);
        
        return mergeSortSub(a,b);
    }
    
    private static int[] mergeSortSub(int[] a,int[] b){
        
        int[] result=new int[a.length+b.length];
        int i=0,j=0,k=0;
        
        while(i<a.length && j<b.length)
        {
            if(a[i]<b[j])
                result[k++]=a[i++];
            else
                result[k++]=b[j++];
        }
        while(i<a.length)
            result[k++]=a[i++];
        while(j<b.length)
            result[k++]=b[j++];
        
        return result;
    }
}