| 3 | 3 | // convenience to get you started writing code faster. |
| 4 | 4 | // |
| 5 | 5 | |
| 6 | | export const solve = () => { |
| 7 | | throw new Error('Remove this line and implement the function'); |
| 6 | export const solve = (puzzle) => { |
| 7 | // Edge Case: Empty or invalid puzzle format |
| 8 | if (!puzzle || typeof puzzle !== 'string') { |
| 9 | return null; |
| 10 | } |
| 11 | |
| 12 | // Parse the puzzle - handle == correctly |
| 13 | const normalizedPuzzle = puzzle.replace(/\s/g, '').replace(/==/g, '='); |
| 14 | const parts = normalizedPuzzle.split(/[\+\=]/); |
| 15 | |
| 16 | // Edge Case: Invalid puzzle format - not enough parts |
| 17 | if (parts.length < 3) { |
| 18 | return null; |
| 19 | } |
| 20 | |
| 21 | const addends = parts.slice(0, -1); |
| 22 | const result = parts[parts.length - 1]; |
| 23 | const allWords = [...addends, result]; |
| 24 | |
| 25 | // Edge Case: Empty words in puzzle |
| 26 | if (allWords.some(word => word.length === 0)) { |
| 27 | return null; |
| 28 | } |
| 29 | |
| 30 | // Get all unique letters in order of first appearance in puzzle |
| 31 | const letters = []; |
| 32 | const seen = new Set(); |
| 33 | for (const char of puzzle) { |
| 34 | if (/[A-Z]/.test(char) && !seen.has(char)) { |
| 35 | seen.add(char); |
| 36 | letters.push(char); |
| 37 | } |
| 38 | } |
| 39 | |
| 40 | // Edge Case: Too many unique letters (more than 10) |
| 41 | if (letters.length > 10) { |
| 42 | return null; |
| 43 | } |
| 44 | |
| 45 | // Get leading letters (first letter of each word) |
| 46 | const leadingLetters = [...new Set(allWords.map(word => word[0]))]; |
| 47 | |
| 48 | // Edge Case: No letters to solve |
| 49 | if (letters.length === 0) { |
| 50 | return null; |
| 51 | } |
| 52 | |
| 53 | // Generate all possible digit permutations for the letters |
| 54 | const permutations = generatePermutations(Array.from({length: 10}, (_, i) => i), letters.length); |
| 55 | |
| 56 | for (const perm of permutations) { |
| 57 | const mapping = {}; |
| 58 | let valid = true; |
| 59 | |
| 60 | // Create mapping from letters to digits |
| 61 | for (let i = 0; i < letters.length; i++) { |
| 62 | mapping[letters[i]] = perm[i]; |
| 63 | } |
| 64 | |
| 65 | // Edge Case: Leading zero constraint |
| 66 | if (leadingLetters.some(letter => mapping[letter] === 0)) { |
| 67 | continue; |
| 68 | } |
| 69 | |
| 70 | // Calculate sum of addends |
| 71 | let sum = 0; |
| 72 | for (const addend of addends) { |
| 73 | let num = 0; |
| 74 | for (const char of addend) { |
| 75 | num = num * 10 + mapping[char]; |
| 76 | } |
| 77 | sum += num; |
| 78 | } |
| 79 | |
| 80 | // Calculate result value |
| 81 | let resultValue = 0; |
| 82 | for (const char of result) { |
| 83 | resultValue = resultValue * 10 + mapping[char]; |
| 84 | } |
| 85 | |
| 86 | // Edge Case: Valid solution found |
| 87 | if (sum === resultValue) { |
| 88 | // Return mapping with keys in alphabetical order for consistency |
| 89 | const orderedMapping = {}; |
| 90 | const sortedKeys = Object.keys(mapping).sort(); |
| 91 | for (const key of sortedKeys) { |
| 92 | orderedMapping[key] = mapping[key]; |
| 93 | } |
| 94 | return orderedMapping; |
| 95 | } |
| 96 | } |
| 97 | |
| 98 | // Edge Case: No solution exists |
| 99 | return null; |
| 8 | 100 | }; |
| 101 | |
| 102 | // Helper function to generate permutations |
| 103 | function generatePermutations(arr, size) { |
| 104 | const result = []; |
| 105 | |
| 106 | function permute(tempArr, remaining) { |
| 107 | if (tempArr.length === size) { |
| 108 | result.push([...tempArr]); |
| 109 | return; |
| 110 | } |
| 111 | |
| 112 | for (let i = 0; i < remaining.length; i++) { |
| 113 | const current = remaining[i]; |
| 114 | const newRemaining = [...remaining.slice(0, i), ...remaining.slice(i + 1)]; |
| 115 | permute([...tempArr, current], newRemaining); |
| 116 | } |
| 117 | } |
| 118 | |
| 119 | permute([], arr); |
| 120 | return result; |
| 121 | } |
| 122 | |
| 123 | // Handled Edge Cases: Empty or invalid puzzle format, Invalid puzzle format - not enough parts, Empty words in puzzle, Too many unique letters (more than 10), No letters to solve, Leading zero constraint, Valid solution found, No solution exists |