diff --git a/strings/string_is_valid_number.py b/strings/string_is_valid_number.py
index cfd941630..073240733 100644
--- a/strings/string_is_valid_number.py
+++ b/strings/string_is_valid_number.py
@@ -4,6 +4,35 @@ Topic: Deterministic Finite Automaton (DFA)
 Given a string s, return whether s is a valid number or not
 Leetcode link: https://leetcode.com/problems/valid-number/description/
 """
+from enum import Enum
+from typing import Dict
+
+class CharType(Enum):
+    NUMERIC = 'NUMERIC'
+    SIGN = 'SIGN'
+    EXPONENT = 'EXPONENT'
+    DECIMAL = 'DECIMAL'
+
+class State(Enum):
+    INITIAL = 'INITIAL'
+    SIGNED = 'SIGNED'
+    WHOLE = 'WHOLE'
+    FRACTIONAL = 'FRACTIONAL'
+    FRACTION = 'FRACTION'
+    EXPONENTIAL = 'EXPONENTIAL'
+    EXP_SIGN = 'EXP_SIGN'
+    EXP_NUMBER = 'EXP_NUMBER'
+
+state_machine : Dict[State, Dict[CharType, State]] = {
+    State.INITIAL: {CharType.NUMERIC: State.WHOLE, CharType.SIGN: State.SIGNED, CharType.DECIMAL: State.FRACTIONAL},
+    State.SIGNED: {CharType.NUMERIC: State.WHOLE, CharType.DECIMAL: State.FRACTIONAL},
+    State.WHOLE: {CharType.NUMERIC: State.WHOLE, CharType.DECIMAL: State.FRACTION, CharType.EXPONENT: State.EXPONENTIAL},
+    State.FRACTIONAL: {CharType.NUMERIC: State.FRACTION},
+    State.FRACTION: {CharType.NUMERIC: State.FRACTION, CharType.EXPONENT: State.EXPONENTIAL},
+    State.EXPONENTIAL: {CharType.NUMERIC: State.EXP_NUMBER, CharType.SIGN: State.EXP_SIGN},
+    State.EXP_SIGN: {CharType.NUMERIC: State.EXP_NUMBER},
+    State.EXP_NUMBER: {CharType.NUMERIC: State.EXP_NUMBER},
+}
 
 from enum import Enum