is valid number

is_valid_number.py

class Solution(object):
    def isNumber(self, s):
        """
        :type s: str
        :rtype: bool
        """
        
        #define state transition tables
        states = [
            # no State (0)
            {},
            # State (1) - Init state
            {'blank': 1, 'sign': 2, 'digit': 3, '.': 4}, 
            # State (2) - Signed - after finding +, -
            {'digit': 3, '.': 4}, 
            # State (3) - Digit
            {'digit': 3, '.': 5, 'e': 6, 'blank': 9},
            # State (4) - Don-digit dot
            {'digit': 5},
            # State (5) - After Dot
            {'digit': 5, 'e':6, 'blank': 9},
            # State (6) - Found 'e'
            {'digit': 8, 'sign': 7},
            # State (7) - Sign After 'e'
            {'digit': 8},
            # State (8) - Digit after 'e'
            {'digit': 8, 'blank': 9},
            # State (9) - Terminal
            {'blank': 9}
        ]
        
        current_state = 1
        for c in s:
            c_type = None
            if c >= '0' and c <='9':
                c_type = 'digit'
            elif c == "-" or c == "+":
                c_type = 'sign'
            elif c == " ":
                c_type = 'blank'
            else:
                c_type = c

            # if we can not move on, we end it here
            if c_type not in states[current_state]:
                return False
            
            current_state = states[current_state][c_type]

        # State 3, 5, 8, 9 are accepted terminal states.
        return current_state in [3, 5, 8, 9]