Valid Number

Validate if a given string is numeric.

Some examples:
"0" => true
" 0.1 " => true
"abc" => false
"1 a" => false
"2e10" => true

Note: It is intended for the problem statement to be ambiguous. You should gather all requirements up front before implementing one.

class Solution:    # @param s, a string    # @return a boolean    def isNumber(self, s):                INVALID=0; SPACE=1; SIGN=2; DIGIT=3; DOT=4; EXPONENT=5;        transitionTable=[[-1,  0,  3,  1,  2, -1],    #0 no input or just spaces                          [-1,  8, -1,  1,  4,  5],    #1 input is digits                          [-1, -1, -1,  4, -1, -1],    #2 no digits in front just Dot                          [-1, -1, -1,  1,  2, -1],    #3 sign                          [-1,  8, -1,  4, -1,  5],    #4 digits and dot in front                          [-1, -1,  6,  7, -1, -1],    #5 input 'e' or 'E'                          [-1, -1, -1,  7, -1, -1],    #6 after 'e' input sign                          [-1,  8, -1,  7, -1, -1],    #7 after 'e' input digits                          [-1,  8, -1, -1, -1, -1]]    #8 after valid input input space        state=0; i=0        while i < len(s) :            inputtype = INVALID            if s[i] ==' ' : inputtype = SPACE            elif s[i] == '+' or s[i] == '-' : inputtype = SIGN            elif s[i] in '0123456789' : inputtype = DIGIT            elif s[i] == '.' : inputtype = DOT            elif s[i] == 'e' or s[i] == 'E': inputtype = EXPONENT            state = transitionTable[state][inputtype]            if state == -1 : return False            i += 1        return state == 1 or state == 4 or state == 7 or state == 8