Valid Number--LeetCode

class Solution {
public:
bool isNumber(string s) {
    if(s == " ") return false;
    int i = 0;
    int j = s.size()-1;
    while(s[i] == ' ') ++i;
    while(s[j] == ' ') --j;
    ++j;

    if(s[i] == '+' || s[i] == '-') ++i;

    if(i == j) return false;

    bool numberic = true;
    bool flag = false;

    int k = scanDigits(s,i,j);
    if (k != i)
    {
        flag = true;
    }

    i = k;

    if(i < j){
        if(s[i] == '.'){
            ++i;
            if(i == j && !flag) return false;
            else
            {
                k = scanDigits(s,i,j);
                if (k != i)
                {
                    flag = true;
                }
                i = k;
                if(i < j && (s[i] == 'E'||s[i] == 'e'))
                    numberic = flag && isExponential(s, (++i),j);
            }

        }
        else if(i < j && (s[i] == 'E'||s[i] == 'e'))
            numberic = flag && isExponential(s, ++i,j);
        else numberic = false;
    }

    return numberic && i == j;

}

int scanDigits(string str, int i,int j){
    while(i < j && str[i] >= '0'&& str[i] <= '9') ++i;
    return i;
}

bool isExponential(string str, int& i, int j){
    if(i == j) return false;
    if(str[i] == '+' || str[i] == '-') ++i;

    if(i == j) return false;
    i = scanDigits(str,i,j);
    return i==j?true:false;
}
};

测试了好多次才过了 太不容易 所以贴个上来做下纪念

".9e1","+.1"  "1."都正确