What is the time complexity of each of the following blocks of code? Briefly justify your answer.

a$)$

for $($int $i=1$;$in$;$i++\{$

for $($int $j=1$;$jn$;$j+=3)\{$

$//$ some $O(1)$ expression

$\}$

$\}$

b$)$

for $($int $i=1$;$in$;$i**=2\{$

$//$ some $O(1)$ expressions

$\}$