// Lightweight LeetCode problem -> DSA pattern classifier.

export const PATTERN_KEYWORDS: [string, string][] = [
  ['two sum', 'Arrays & Hashing'],
  ['hash', 'Arrays & Hashing'],
  ['anagram', 'Arrays & Hashing'],
  ['duplicate', 'Arrays & Hashing'],
  ['contains', 'Arrays & Hashing'],
  ['group', 'Arrays & Hashing'],
  ['array', 'Arrays & Hashing'],
  ['interval', 'Intervals'],
  ['meeting', 'Intervals'],
  ['slots', 'Intervals'],
  ['skyline', 'Intervals'],
  ['two pointers', 'Two Pointers'],
  ['palindrome', 'Two Pointers'],
  ['three sum', 'Two Pointers'],
  ['3sum', 'Two Pointers'],
  ['container', 'Two Pointers'],
  ['sliding window', 'Sliding Window'],
  ['substring', 'Sliding Window'],
  ['subarray', 'Sliding Window'],
  ['stack', 'Stack'],
  ['parentheses', 'Stack'],
  ['binary search', 'Binary Search'],
  ['binary', 'Binary Search'],
  ['search in', 'Binary Search'],
  ['koko', 'Binary Search'],
  ['median', 'Binary Search'],
  ['sqrt', 'Binary Search'],
  ['linked list', 'Linked List'],
  ['remove nth', 'Linked List'],
  ['merge two', 'Linked List'],
  ['reverse', 'Linked List'],
  ['cycle', 'Linked List'],
  ['binary tree', 'Trees'],
  ['inorder', 'Trees'],
  ['preorder', 'Trees'],
  ['level order', 'Trees'],
  ['max depth', 'Trees'],
  ['lowest common', 'Trees'],
  ['tree', 'Trees'],
  ['bst', 'Trees'],
  ['graph', 'Graphs'],
  ['course schedule', 'Graphs'],
  ['number of islands', 'Graphs'],
  ['island', 'Graphs'],
  ['topological', 'Graphs'],
  ['word ladder', 'Graphs'],
  ['heap', 'Heaps'],
  ['priority', 'Heaps'],
  ['kth largest', 'Heaps'],
  ['top k', 'Heaps'],
  ['backtracking', 'Backtracking'],
  ['combination', 'Backtracking'],
  ['permutation', 'Backtracking'],
  ['subsets', 'Backtracking'],
  ['letter combinations', 'Backtracking'],
  ['dynamic programming', 'Dynamic Programming'],
  [' dp ', 'Dynamic Programming'],
  ['coin change', 'Dynamic Programming'],
  ['house robber', 'Dynamic Programming'],
  ['climbing stairs', 'Dynamic Programming'],
  ['unique paths', 'Dynamic Programming'],
  ['word break', 'Dynamic Programming'],
  ['longest', 'Dynamic Programming'],
  ['edit distance', 'Dynamic Programming'],
  ['regex', 'Dynamic Programming'],
  ['wildcard', 'Dynamic Programming'],
  ['decode', 'Dynamic Programming'],
  ['partition equal', 'Dynamic Programming'],
  ['subsequence', 'Dynamic Programming'],
  ['paint house', 'Dynamic Programming'],
  ['trie', 'Trie'],
  ['prefix', 'Trie'],
  ['implement trie', 'Trie'],
  ['bit', 'Bit Manipulation'],
  ['xor', 'Bit Manipulation'],
  ['missing number', 'Bit Manipulation'],
  ['string to integer', 'Math'],
  ['reverse integer', 'Math'],
  ['pow', 'Math'],
  ['math', 'Math'],
  ['sqrt', 'Math'],
  ['lru', 'Design'],
  ['design', 'Design'],
  ['min stack', 'Design'],
  ['serialize', 'Design'],
  ['union find', 'Union Find'],
  ['redundant', 'Union Find'],
  ['alien', 'Union Find'],
  ['greedy', 'Greedy'],
  ['jump game', 'Greedy'],
  ['best time', 'Greedy'],
  ['maximum subarray', 'Greedy'],
  ['divid', 'Divide & Conquer'],
  ['sort an array', 'Sorting'],
  ['merge sorted', 'Sorting'],
  ['k closest', 'Heaps'],
  ['k smallest', 'Heaps'],
  ['k nearest', 'Heaps'],
  ['find k', 'Heaps'],
  ['top k', 'Heaps'],
  ['matrix', 'Matrix'],
  ['rotate', 'Matrix'],
  ['spiral', 'Matrix'],
  ['sudoku', 'Matrix'],
  ['set matrix', 'Matrix'],
];

export function classifyPattern(title: string): string {
  const lower = ` ${title.toLowerCase()} `;
  for (const [kw, pattern] of PATTERN_KEYWORDS) {
    if (lower.includes(` ${kw} `) || lower.includes(kw)) return pattern;
  }
  return 'Core Algorithms';
}