65. Valid Number

class Solution {
    public boolean isNumber(String s) {
        s=s.trim();
        int idx=s.indexOf('e');
        if(idx>0)
            return isNum(s.substring(0,idx), false)&&isNum(s.substring(idx+1), true);
        return isNum(s, false);
    }
    private boolean isNum(String s, boolean dot){
        if(s.length()==0)
            return false;
        int numlen=0;
        for(int i=0;i<s.length();i++)
        {
            if(s.charAt(i)>='0'&&s.charAt(i)<='9')
                numlen++;
            else if(i==0&&(s.charAt(i)=='+'||s.charAt(i)=='-'))
                continue;
            else if(s.charAt(i)=='.'&&dot==false)
                dot=true;
            else
                return false;
        }
        return numlen>0;
    }
}