| 1 | import itertools |
| 2 | import re |
| 3 | |
| 1 | 4 | def solve(puzzle: str) -> dict[str, int] | None: |
| 2 | | pass |
| 5 | # Parse the puzzle into words |
| 6 | # Edge Case: Invalid puzzle format |
| 7 | if '==' not in puzzle: |
| 8 | # Try to handle single equation (no ==) |
| 9 | parts = puzzle.replace('=', '==').split('==') |
| 10 | if len(parts) != 2: |
| 11 | return None |
| 12 | left_side, right_side = parts[0].strip(), parts[1].strip() |
| 13 | else: |
| 14 | parts = puzzle.split('==') |
| 15 | if len(parts) != 2: |
| 16 | return None |
| 17 | left_side, right_side = parts[0].strip(), parts[1].strip() |
| 18 | |
| 19 | # Extract all words (sequences of letters) |
| 20 | words = re.findall(r'[A-Z]+', puzzle) |
| 21 | |
| 22 | # Edge Case: No words found |
| 23 | if not words: |
| 24 | return None |
| 25 | |
| 26 | # Get all unique letters |
| 27 | unique_letters = set(''.join(words)) |
| 28 | |
| 29 | # Edge Case: More than 10 unique letters (impossible to solve) |
| 30 | if len(unique_letters) > 10: |
| 31 | return None |
| 32 | |
| 33 | # Get first letters of each word (can't be zero) |
| 34 | first_letters = {word[0] for word in words} |
| 35 | |
| 36 | # Edge Case: Empty words |
| 37 | if any(len(word) == 0 for word in words): |
| 38 | return None |
| 39 | |
| 40 | # Try all permutations of digits for the unique letters |
| 41 | digits = range(10) |
| 42 | for perm in itertools.permutations(digits, len(unique_letters)): |
| 43 | mapping = dict(zip(unique_letters, perm)) |
| 44 | |
| 45 | # Edge Case: Leading zero |
| 46 | if any(mapping[letter] == 0 for letter in first_letters): |
| 47 | continue |
| 48 | |
| 49 | # Convert words to numbers using the current mapping |
| 50 | def word_to_number(word): |
| 51 | return int(''.join(str(mapping[letter]) for letter in word)) |
| 52 | |
| 53 | # Parse and evaluate the left side |
| 54 | # Split by + and - to handle addition and subtraction |
| 55 | # We need to be careful with the parsing |
| 56 | |
| 57 | # Convert words to numbers and evaluate the equation |
| 58 | try: |
| 59 | # Parse the left side and right side separately |
| 60 | # Handle different operators (+, -, *) |
| 61 | |
| 62 | # Process left side - handle different operators |
| 63 | # Find all words and operators in the left side |
| 64 | tokens = re.findall(r'[A-Z]+|[+*-]', left_side) |
| 65 | |
| 66 | if not tokens: |
| 67 | continue |
| 68 | |
| 69 | # Convert words to numbers and evaluate |
| 70 | left_value = 0 |
| 71 | current_op = '+' |
| 72 | first_number = True |
| 73 | |
| 74 | for token in tokens: |
| 75 | if token in ['+', '-', '*']: |
| 76 | current_op = token |
| 77 | else: |
| 78 | # Convert word to number |
| 79 | word_value = int(''.join(str(mapping[letter]) for letter in token)) |
| 80 | |
| 81 | if first_number: |
| 82 | left_value = word_value |
| 83 | first_number = False |
| 84 | elif current_op == '+': |
| 85 | left_value += word_value |
| 86 | elif current_op == '-': |
| 87 | left_value -= word_value |
| 88 | elif current_op == '*': |
| 89 | left_value *= word_value |
| 90 | |
| 91 | # Process right side |
| 92 | right_words = re.findall(r'[A-Z]+', right_side) |
| 93 | if len(right_words) != 1: |
| 94 | continue |
| 95 | right_value = int(''.join(str(mapping[letter]) for letter in right_words[0])) |
| 96 | |
| 97 | # Check if equation is satisfied |
| 98 | if left_value == right_value: |
| 99 | return mapping |
| 100 | except: |
| 101 | # If there's any error in evaluation, continue to next permutation |
| 102 | continue |
| 103 | |
| 104 | # Edge Case: No solution found |
| 105 | return None |
| 106 | # Handled Edge Cases: Invalid puzzle format, No words found, More than 10 unique letters, Empty words, Leading zero, Malformed expression, No solution found |