Crossword Generator

A TypeScript library for generating crossword puzzles from a list of words. The library creates clean, properly intersecting crossword grids with intelligent word placement and validation.

Features

• ✅ Smart Word Placement: Uses intersection-based algorithm to place words naturally
• ✅ Randomization: Each generation produces different puzzles from the same word list
• ✅ Clean Validation: Prevents accidental word formations and invalid letter sequences
• ✅ Flexible Grid Sizing: Configurable maximum grid dimensions
• ✅ Multiple Output Formats: Terminal display, JSON, and various formatting options
• ✅ TypeScript Support: Full type definitions included

Installation

npm install crossword-generator

Quick Start

import { generateCrossword } from 'crossword-generator';

const words = ['ARTIST', 'OCTAGON', 'ANGLE', 'DESERT', 'FORCE', 'RENDER', 'PUZZLE'];
const result = generateCrossword(words, { 
  wordCount: 7,
  maxGridSize: 15 
});

console.log(result.grid);
// [
//   [null, null, null, null, null, 'D'],
//   ['P', 'U', 'Z', 'Z', 'L', 'E'],
//   [null, null, null, null, null, 'S'],
//   [null, 'F', 'O', 'R', 'C', 'E'],
//   [null, null, 'C', null, null, 'R'],
//   ['A', 'R', 'T', 'I', 'S', 'T'],
//   [null, null, 'A', null, null, null],
//   ['A', 'N', 'G', 'L', 'E', null],
//   [null, null, 'O', null, null, null],
//   ['R', 'E', 'N', 'D', 'E', 'R']
// ]

API Reference

generateCrossword(words, options?)

Generates a crossword puzzle from an array of words.

Parameters:

• words: string[] - Array of words to use for the crossword
• options?: CrosswordOptions - Configuration options (optional)

Returns: CrosswordResult

CrosswordOptions

| Option | Type | Default | Description | |--------|------|---------|-------------| | wordCount | number | 10 | Target number of words to include. The library tries to achieve this count, but may place fewer words if intersections cannot be found or grid constraints prevent placement. | | maxGridSize | number | 15 | Maximum grid dimensions (both width and height). Only words shorter than this length will be considered. | | maxAttempts | number | 1000 | Maximum number of generation attempts to find the best crossword. | | validationLevel | 'strict' \| 'normal' \| 'lenient' | 'normal' | Word placement validation strictness. | | minWordLength | number | 3 | Minimum word length to consider. | | maxWordLength | number | maxGridSize | Maximum word length to consider. |

CrosswordResult

{
  grid: (string | null)[][];     // 2D array representing the crossword
  placedWords: PlacedWord[];     // Information about placed words
  stats: {
    wordsUsed: number;           // Actual number of words placed
    gridSize: { width: number; height: number };
    totalIntersections: number;
    attempts: number;
  };
}

PlacedWord

{
  word: string;                  // The word text
  startRow: number;              // Starting row position
  startCol: number;              // Starting column position
  direction: 'horizontal' | 'vertical';
  endRow: number;                // Ending row position
  endCol: number;                // Ending column position
}

Display Functions

The library includes several formatting functions for displaying crosswords:

Terminal Display

import { generateCrossword, formatCrosswordForTerminal } from 'crossword-generator';

const result = generateCrossword(words, { wordCount: 10 });
console.log(formatCrosswordForTerminal(result));

Output:

    0  1  2  3  4  5 
 0  ·  ·  ·  ·  ·  D 
 1  P  U  Z  Z  L  E 
 2  ·  ·  ·  ·  ·  S 
 3  ·  F  O  R  C  E 
 4  ·  ·  C  ·  ·  R 
 5  A  R  T  I  S  T 
 6  ·  ·  A  ·  ·  · 
 7  A  N  G  L  E  · 
 8  ·  ·  O  ·  ·  · 
 9  R  E  N  D  E  R 

Words used:
1. ARTIST → (5, 0)
2. OCTAGON ↓ (3, 2)
3. ANGLE → (7, 0)
4. DESERT ↓ (0, 5)
5. FORCE → (3, 1)
6. RENDER → (9, 0)
7. PUZZLE → (1, 0)

Other Display Options

import { 
  formatCompact,
  formatDetailed,
  formatClean,
  printCrossword
} from 'crossword-generator';

// Print directly to console
printCrossword(result);

// Get formatted strings
const compact = formatCompact(result);      // Minified JSON
const detailed = formatDetailed(result);    // Full details with stats
const clean = formatClean(result);          // Clean array format

Examples

Basic Usage

import { generateCrossword } from 'crossword-generator';

const words = ['CAT', 'DOG', 'BIRD', 'FISH'];
const crossword = generateCrossword(words, {
  wordCount: 4,
  maxGridSize: 10
});

console.log(`Generated crossword with ${crossword.stats.wordsUsed} words`);

Large Word List

import { generateCrossword } from 'crossword-generator';

const words = [
  'JAVASCRIPT', 'TYPESCRIPT', 'REACT', 'NODE', 'EXPRESS',
  'DATABASE', 'API', 'FRONTEND', 'BACKEND', 'FULLSTACK',
  // ... 200+ more words
];

const crossword = generateCrossword(words, {
  wordCount: 25,        // Try to place 25 words
  maxGridSize: 20,      // Allow larger grid
  maxAttempts: 2000,    // More attempts for complex puzzles
  validationLevel: 'normal'
});

// Note: Actual words placed might be less than 25 if intersections can't be found
console.log(`Placed ${crossword.stats.wordsUsed} out of ${words.length} available words`);

Custom Configuration

const crossword = generateCrossword(words, {
  wordCount: 15,           // Target 15 words (may place fewer)
  maxGridSize: 12,         // Compact 12x12 maximum grid
  minWordLength: 4,        // Only words with 4+ letters
  maxWordLength: 10,       // No words longer than 10 letters
  validationLevel: 'strict', // Strictest validation
  maxAttempts: 500         // Fewer attempts for faster generation
});

Algorithm Details

The crossword generation algorithm:

1. Word Selection: Randomly selects words from the input array based on length constraints
2. First Placement: Places the first word randomly in the center area of the grid
3. Intersection Finding: For each subsequent word, finds all possible intersection points with existing words
4. Validation: Ensures new word placement doesn't create invalid letter sequences or accidental words
5. Optimization: Tries multiple attempts to find the best crossword configuration
6. Grid Trimming: Removes empty rows and columns for a compact final result

Important Notes

• Word Count: The wordCount option represents a target that the library tries to achieve. The actual number of words placed may be lower if:
  • No valid intersections can be found
  • Grid size constraints prevent placement
  • Validation rules reject potential placements
• Grid Output: The returned grid is a 2D array where string represents letters and null represents empty cells
• Word Selection: Words longer than maxGridSize are automatically filtered out
• Randomization: Each call produces different results even with identical inputs

TypeScript Support

The library is written in TypeScript and includes full type definitions. All types are exported for use in your projects:

import { 
  CrosswordOptions, 
  CrosswordResult, 
  PlacedWord,
  CrosswordGrid,
  Direction 
} from 'crossword-generator';

License

MIT

Contributing

Issues and pull requests are welcome! Please ensure all tests pass and follow the existing code style.