Function bar$($a: array, size: int$)=>$ int

if size $==0$:

return a$[$size$]$

else:

total $=0$

for j in $0$ to size:

total $=$ total $+$ a$[$j$]$

return total $+$ bar$($arr$,$ size$-2)$

Initial call: bar$($a$,$ a$.$length$),$ where a is an integer array.

Express the running time of the above method using the big$-$O notation.