LeetCode第八题--字符串转整数

字符型数字减去字符‘0’就能得到对应的数字形式

class Solution {
public:
 int myAtoi(string s) {
 unsigned long len s.length();
 int index 0;
 while(index len){
 if(s[index]! ) break;
 index ;
 if(index len) return 0;
 int sign 1;
 int res 0;
 if(s[index] ) index ;
 else if(s[index] - ){
 index ;
 sign -1;
 while(index len){
 char c s[index];
 if(c 0 ||c 9 ) break;
 if(res INT_MAX/10||(res INT_MAX/10) ((c- 0 ) INT_MAX%10)) return INT_MAX;
 if(res INT_MIN/10||(res INT_MIN/10) ((c- 0 ) -(INT_MIN%10))) return INT_MIN;
 res res*10 sign*(c - 0 );
 index ;
 return res;

class Solution:
 def myAtoi(self, s: str) - int:
 index, res, sign 0, 0, 1
 while index len(s) and s[index] :
 index index 1
 if len(s) 0 or index len(s):
 return 0
 if s[index] - :
 sign -1
 if s[index] or s[index] - :
 index index 1
 while index len(s) and 0 s[index] 9 :
 c int(s[index])
 res res*10 c*sign
 index 1
 if res -2**31: return -2**31
 elif res 2**31-1: return 2**31-1
 return res