Leetcode 8. 字符串转换整数 (atoi)（DAY 165）---- LeetCode 精选 TOP 面试题

港控/mmm° 2022-09-10 12:22 155阅读 0赞

### 文章目录 ###

*   *  原题题目
     *  代码实现（首刷自解）

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## 原题题目 ##

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## 代码实现（首刷自解） ##

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class Solution { 
    public:
        int myAtoi(string s) { 
            bool neg = false,wrong = false,numend = false,dealnum = false;;
            long ret = 0;
            int numdeal = -1;
            for(int i=0;i<s.size();++i)
            { 
                char chr = s[i];
                if(chr != ' ' && chr != '-' && chr != '+'  && (chr > '9' || chr < '0'))
                { 
                    wrong = true;
                    break;
                }
                if(chr == ' ')  continue;
                else if(chr == '-' || chr == '+' || (chr >= '0' && chr <= '9'))
                { 
                    if(chr == '-')  neg = true;
                    numdeal = i;
                    if(chr == '-' || chr == '+')    ++numdeal;
                    break;
                }       
            }
            
            if(numdeal == -1)   wrong = true;
            for(int i=numdeal;!wrong && i<s.size();++i)
            { 
                char chr = s[i];
                if(chr < '0' || chr > '9')    
                { 
                    if(numend) wrong = true;
                    else numend = true;
                    break;
                }
                else
                { 
                    ret *= 10;
                    ret += (chr - '0');
                    if(ret > INT_MAX)
                    { 
                        if(neg) ret = INT_MIN;
                        else    ret = INT_MAX;
                        dealnum = true;
                        break;
                    }
                }
            }
    
            if(!dealnum) ret = (neg) ? -ret : ret; 
            if(wrong)   ret = 0;
            return (int)ret;
        }
    };

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