mergeSortInCpp.cpp

{
    public:
    void merge(int arr[], int l, int m, int r)
    {
        int n1= m-l+1;
        int n2 = r-m;
        int a[n1],b[n2];
        
        for(int i =0; i<n1; i++)
        {
            a[i]=arr[l+i];
        }
        for(int i =0; i<n2; i++)
        {
            b[i]=arr[m+i+1];
        }
        
        int i = 0,j = 0;
        int k =l;
    
        while(i<n1 && j<n2)
        {
            if(a[i]<b[j])
            {
                arr[k]=a[i];
                i++,k++;
            }
            else
            {
                arr[k]=b[j];
                j++,k++;
            }
        }
        while(i<n1)
        {
            arr[k]=a[i];
            i++,k++;
        }
        while(j<n2)
        {
            arr[k]=b[j];
            j++,k++;
        }
        
    }
    public:
    void mergeSort(int arr[], int l, int r)
    {
        if(l<r){
            int mid = (l+r)/2;
            mergeSort(arr,l,mid);
            mergeSort(arr,mid+1,r);
            merge(arr,l,mid,r);
        }
    }
};