Swift.把字符串转换成整数

题目描述：将一个字符串转换成一个整数，要求不能使用字符串转换整数的库函数。 i c } m l p a o s r s f } t u F n F o c o r g } l v l v i } } } i } v f } r u 4 m u e a e a f e e f a o e n 9 y a t r t r l l r r t d S A r a s s b u a o t d r a b c s r b s e b e r e r s i i } i } i } s r t l o e r e o i r e i e e g e u f f f u n i u i s t r g u g [ g g i g i t i t m i m o t ( t u i n n 0 i n f i f u n u n a s s s n i _ r r = n t ] n n r r = r r i r i r = u o . n = = a a n > n b r e g e g e m n s c A = = = + r + r 0 e [ t n t n t s t o 0 r 1 = = - r = r 0 c 0 g i u u u u { r u r 0 s 1 [ [ o i ] r = r = r m : n a t " 1 0 1 0 u n n = n = n t y r - ] ] n . s c = - g I ( > " n I a 9 t n r " " ( t r 9 S ( [ " { t S i r t ] { i r ) n i ) g n ! ( g * a ( s r a i r r g [ r n i [ ] i ) ] ) ) ! ) * ! s * i s g i n g ) n / ) 1 / 0 1 0 s u s m u m { { github地址：https://github.com/cubegao/LeetCode