class Solution:
    def isNumber(self, s: str) -> bool:
        try:
            float(s)
            return True
        except ValueError:
            return False

class Solution:
    def isNumber(self, s: str) -> bool:
        states = [
            { ' ': 0, 's': 1, 'd': 2, '.': 4 }, # 0. start with 'blank'
            { 'd': 2, '.': 4 } ,                # 1. 'sign' before 'e'
            { 'd': 2, '.': 3, 'e': 5, ' ': 8 }, # 2. 'digit' before 'dot'
            { 'd': 3, 'e': 5, ' ': 8 },         # 3. 'digit' after 'dot'
            { 'd': 3 },                         # 4. 'digit' after 'dot' (‘blank’ before 'dot')
            { 's': 6, 'd': 7 },                 # 5. 'e'
            { 'd': 7 },                         # 6. 'sign' after 'e'
            { 'd': 7, ' ': 8 },                 # 7. 'digit' after 'e'
            { ' ': 8 }                          # 8. end with 'blank'
        ]
        p = 0                           # start with state 0
        for c in s:
            if '0' <= c <= '9': 
                t = 'd' # digit
            elif c in "+-": 
                t = 's'     # sign
            elif c in "eE": 
                t = 'e'     # e or E
            elif c in ". ": 
                t = "."       # dot, blank
            else: 
                t = '?'               # unknown
            if t not in states[p]: 
                return False
            p = states[p][t]
        return p in (2, 3, 7, 8)