Data-Structures-/mergesort at master · ritikaraws/Data-Structures- · GitHub

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public class mergesorting {
    public static void sort( int a[],int l,int r)
    {
      if(l<r)
      {
          int mid=(l+r)/2;
          sort(a, l,mid);
          sort(a, mid+1,r);
          merge(a,l,mid,r);

      }
    }
    public static void merge(int a[],int l,int mid,int r)
     {
        int nl=mid-l+1;
        int nr=r-mid;
        int larr[]=new int [nl];
        for(int i=0;i<nl;i++)
        {
            larr[i]=a[l+i];
        }
        int rarr[]=new int [nr];
        for(int j=0;j<nr;j++)
        {
            rarr[j]=a[mid+1+j];
        }
        int i=0,j=0,k=l;
        while(i<nl&&j<nr)
        {
            if(larr[i]<rarr[j])
            {
                a[k]=larr[i];
                i++;
                k++;
            }
            else
            {
                a[k]=rarr[j];
                j++;
                k++;
            }
        }
        while(i<nl)
        {
            a[k]=larr[i];i++;k++;
        }
        while(j<nr)
        {
            a[k]=rarr[j];j++;k++;
        }
    }


public static void main (String args[])
{
    int a[]={20,10,15,5,25};
    int l=0;
    int r=a.length - 1;
    for(int i=0;i<=r;i++)
    {
        System.out.print(a[i] + " ");
    }
    System.out.println();
    System.out.print("after merge sorting");
    System.out.println();

    sort(a, l, r);
    for(int i=0;i<=r;i++)
    {
        System.out.print(a[i] + " ");
    }

}
}