which has a smaller Big O time complexity? def atoiR$1($string$,$ num$)$:

if len$($string$)==0$:

return $0$

if len$($string$)==1$:

return int$($string$)+($num$*10)$

num $=$ int$($string$[0$:$1])+($num $*10)$

return atoiR$1($string$[1$:$],$ num$)$

def atoiR$2($string$)$:

if len$($string$)==0$:

return $0$

if len$($string$)==1$:

return int$($string$)$

return atoiR$2($string$[0$:$-1])*10+$ int$($string$[-1])$