Find the cost function of the following algorithm and express the upper bound of the time

complexity in asymptotic notation. $(2$ marks$)$

a$.$ sum$=0$;

for i$=0$ to i$=$n do

for j$=0$ to j $=$ i do

$2$

if j mod i $==0$ then

sum$=$sum$+1$;

b$.$ IsPrime$($N$)//$check whether N is a prime number

$\{$

Int i$=3$;

if N$==2$ or N$==3$ then

return TRUE;

if N mod $2==0$ then

return FALSE;

while i do

$2$

$<$ N

$\{$

if N mod i$==0$ then

return FALSE;

else

i $=$ i $+2$;

$\}$

return TRUE;

$\}$