问如何分析程序中所有递归调用的控制流程？

EN

static int [] MergeSortt(int [] A2)
{
    if(A2.length<=1)
    {
    return A2;
    }
int mid=A2.length/2;    
int [] left;
int[] right;
int [] result;

left= new int [mid];

    if(A2.length%2==0)
    {
        right= new int[mid];
    }
    else
    {
        right = new int [mid+1];
    }

    result = new int[A2.length];

    for(int i=0;i<mid;i++)
    {
        left[i]= A2[i];
    }
    int x=0;
    for(int j=mid;j<A2.length;j++)
    {
        if(x<A2.length)
        {
            right[x]= A2[j];
            x++;
        }
    }
    left =MergeSortt(left);
    right=  MergeSortt(right);

    result = merge(left,right);

    return result;
}