When all elements in the input array A are the same, is it the best case or worst case for the INSERTION$-$SORT function below? Why? $(35$ points$)$

INSERTION$-$SORT $(A)$

for $j=2$ to $A.$length

key $=A[j]$

$//$ Insert $A[j]$ into the sorted

sequence $A[1$dotsj$-1].$

$i=j-1$

while $i>0$ and $A[i]>$key

$A[i+1]=A[i]$

$i=i-1$

$A[i+1]=$key