题目描述

blablabla

样例

blablabla

算法1

class Solution {
public:
    int strToInt(string str) {
        long long res=0;
        bool isneg=false;
        int i=0,j=str.size();
        while (i<j && str[i]==' ') i++;
        if (str[i]=='-') i++,isneg=true;
        else if (str[i]=='+') i++;
        else if (!(str[i]>='0' && str[i]<='9')) return 0;
        for (;i<j && str[i]>=0 && str[i]<='9';i++) {
            if (isneg) res=res*10-(str[i]-'0');
            else res=res*10+str[i]-'0';
        }
        if (res>INT_MAX) res=INT_MAX;
        else if (res<INT_MIN) res=INT_MIN;
        return res;
    }
};