LeetCode "Valid Number"

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It took me +20 submissions to get AC... Actually the statement is too vague. I would rather ask for requirements f2f.

Apparently the code below can be simplified..

class Solution {public:    bool isPureNum(string s, int radix)    {                if (s.length() > 1 && s[s.length() - 1] == ‘.‘)        {            s = s.substr(0, s.length() - 1);        }        int i = 0;        while(i < s.length())        {            char c = s[i++];            switch(radix)            {            case 10:                if(!(c >= ‘0‘ && c <= ‘9‘)) return false;                break;            case 16:                if(!((c >= ‘0‘ && c <= ‘9‘) || (c >= ‘a‘ && c <= ‘f‘))) return false;                break;            }        }        return true;    }    bool isFloat(string str)    {        size_t pos = str.find(‘.‘, 0);        string s1 = str.substr(0, pos);        if(s1.find(‘.‘, 0) != string::npos) return false;        string s2 = str.substr(pos + 1, str.length() - pos - 1);        if(s2.find(‘.‘, 0) != string::npos) return false;        if (s1.empty() && s2.empty()) return false;        return isPureNum(s1, 10) &&                 isPureNum(s2, 10);    }    bool isNumber(const char *s) {        int len = strlen(s);        if(len == 0) return false;        //    Trim        int il = 0, ir = len - 1;        while(*(s + il) == ‘ ‘) il ++;        while(*(s + ir) == ‘ ‘) ir --;        if(ir < il) return false;        //    ToLower        string str; str.assign(s + il, s + ir + 1);        std::transform(str.begin(), str.end(), str.begin(), ::tolower);        if(str[0] == ‘-‘ || str[0] == ‘+‘) str = str.substr(1, str.length() - 1);        len = str.length();        char c = str[0];        size_t pos1 = str.find(‘e‘, 0);        if(pos1 != string::npos)        {            //    2e10            string s1 = str.substr(0, pos1);            if(s1.empty()) return false;            if(s1.find(‘e‘, 0) != string::npos) return false;            string s2 = str.substr(pos1 + 1, str.length() - pos1 - 1);            if(s2.find(‘e‘, 0) != string::npos) return false;            if(s2.find(‘.‘, 0) != string::npos) return false;                                if(s2[0] == ‘-‘ ||s2[0] == ‘+‘) s2 = s2.substr(1, s2.length() - 1);            if(s2.empty()) return false;            return (isPureNum(s1, 10) || isFloat(s1)) &&                     isPureNum(s2, 10);        }        else        {            if(isdigit(c))            {                if(len == 1) return true;                if(str[1] == ‘x‘)                {                    if(str[0] == ‘0‘)    return isPureNum(str.substr(2, str.length() - 2), 16);                    else return false;                }                else                {                    size_t pos = str.find(‘.‘, 0);                                if(pos != string::npos)                    {                        //    float                        string s1 = str.substr(0, pos);                        if(s1.find(‘.‘, 0) != string::npos) return false;                        string s2 = str.substr(pos + 1, str.length() - pos - 1);                        if(s2.find(‘.‘, 0) != string::npos) return false;                        if(s2.find(‘+‘, 0) != string::npos) return false;                        if(s2.find(‘-‘, 0) != string::npos) return false;                        if (s1.empty() && s2.empty()) return false;                        return isPureNum(s1, 10) &&                                isPureNum(s2, 10);                    }                    return isPureNum(str, 10);                }            }            else if (c == ‘.‘)    // ".123"            {                string s2 = str.substr(1, str.length() - 1);                if(s2.find(‘.‘, 0) != string::npos) return false;                if(s2.find(‘ ‘, 0) != string::npos) return false;                if(s2.find(‘+‘, 0) != string::npos) return false;                if(s2.find(‘-‘, 0) != string::npos) return false;                return isNumber(s2.c_str());            }        }        return false;    }};