FTPrep, 8 atoi

来源：互联网发布：51单片机时钟电路图编辑：程序博客网时间：2024/06/05 14:41

和上一题 reverse integer 有类似之处，但还多了几个checking的地方：

1，trim leading and trailing whitespace, just use str.trim()

2，check the 1st letter.

3，check char type must be digit, there should be a function, but it is also easy to just write <'0' or >'9'

4，overflow，both MAX_VALUE and MIN_VALUE

效率80+%

public class Solution {    public int myAtoi(String str) {        if(str.length()==0) return 0;        String s=str.trim();        int len=s.length();        boolean isNeg=false;          int i=0;        if(s.charAt(i)=='-') isNeg=true;        int result=0;        int digit=0;        if(s.charAt(i)=='-'||s.charAt(i)=='+') i++;        while(i<len){            if(s.charAt(i)>'9' ||s.charAt(i)<'0' ) break;            digit = s.charAt(i)-'0';            if(isNeg && -result<(Integer.MIN_VALUE+digit)/10) return Integer.MIN_VALUE;            if(!isNeg && result>(Integer.MAX_VALUE-digit)/10) return Integer.MAX_VALUE;            result = result*10+digit;            ++i;        }                return isNeg?-result:result;    }}

阅读全文

0 0