For the algorithm given below,

Input: an array, 'arr' of length n

Output: reversed array, 'arr'

def reverse$\_$array$($arr$)$:

left, rigght $=0,$ len$($arr$)-1$

while left $$ right:

arr$[$left$],$ arr$[$right$]=$ arr$[$right$],$ arr$[$left$]$

left $+=1$

right $-=1$

a$.$ State the loop invariant.

b$.$ Use the invariant to prove that the postcondition is satisfied.

c$.$ Show that the algorithm terminates.