Mege Sort

mergesort.java

public class MergeSorter 
{
    private static int[] a, b;

    public static void sort(int[] c)
    {
        a=c;
        int n=a.length;
        b=new int[(n+1)/2];
        mergesort(0, n-1);
    }

    private static void mergesort(int lo, int hi)
    {
        if (lo<hi)
        {
            int m=(lo+hi)/2;
            mergesort(lo, m);
            mergesort(m+1, hi);
            merge(lo, m, hi);
        }
    }

    private static void merge(int lo, int m, int hi)
    {
        int i, j, k;
        i=0; j=lo;
        
        while (j<=m)
            b[i++]=a[j++];

        i=0; k=lo;
        while (k<j && j<=hi)
            if (b[i]<=a[j])
                a[k++]=b[i++];
            else
                a[k++]=a[j++];
                
        while (k<j)
            a[k++]=b[i++];
    }

}