| 1 | 1 | def solve(puzzle: str) -> dict[str, int] | None: |
| 2 | | pass |
| 2 | # Parse the puzzle |
| 3 | if "==" in puzzle: |
| 4 | left, right = puzzle.split("==") |
| 5 | else: |
| 6 | left, right = puzzle.split("=") |
| 7 | |
| 8 | # Handle both sides of the equation |
| 9 | left_parts = [part.strip() for part in left.split("+")] |
| 10 | right = right.strip() |
| 11 | |
| 12 | # Extract all unique letters |
| 13 | letters = set() |
| 14 | for part in left_parts + [right]: |
| 15 | letters.update(part) |
| 16 | |
| 17 | # Edge Case: More than 10 unique letters (impossible to solve) |
| 18 | if len(letters) > 10: |
| 19 | return None |
| 20 | |
| 21 | # Edge Case: Empty input or malformed puzzle format |
| 22 | if not letters: |
| 23 | return None |
| 24 | |
| 25 | # Get leading letters (can't be zero) |
| 26 | leading_letters = {word[0] for word in left_parts + [right]} |
| 27 | |
| 28 | # Convert to list for indexing |
| 29 | letters = list(letters) |
| 30 | |
| 31 | # Try all permutations of digits for letters |
| 32 | from itertools import permutations |
| 33 | |
| 34 | for perm in permutations(range(10), len(letters)): |
| 35 | mapping = dict(zip(letters, perm)) |
| 36 | |
| 37 | # Edge Case: Leading letters cannot be zero |
| 38 | if any(mapping[letter] == 0 for letter in leading_letters): |
| 39 | continue |
| 40 | |
| 41 | # Calculate left side sum |
| 42 | left_sum = 0 |
| 43 | for word in left_parts: |
| 44 | num = 0 |
| 45 | for char in word: |
| 46 | num = num * 10 + mapping[char] |
| 47 | left_sum += num |
| 48 | |
| 49 | # Calculate right side value |
| 50 | right_num = 0 |
| 51 | for char in right: |
| 52 | right_num = right_num * 10 + mapping[char] |
| 53 | |
| 54 | # Check if equation is satisfied |
| 55 | if left_sum == right_num: |
| 56 | return mapping |
| 57 | |
| 58 | # Edge Case: No solution exists for the given puzzle |
| 59 | return None |