Shuffle Array (Fisher-Yates Algorithm)

/**
 * Shuffle array using Fisher-Yates (Knuth) algorithm
 * @param arr Array to shuffle
 * @returns New shuffled array (original remains unchanged)
 */
function shuffleArray<T>(arr: T[]): T[] {
  const array = [...arr];
  for (let i = array.length - 1; i > 0; i--) {
    const j = Math.floor(Math.random() * (i + 1));
    [array[i], array[j]] = [array[j], array[i]];
  }
  return array;
}

// Usage Example
const numbers = [1, 2, 3, 4, 5];
const shuffled = shuffleArray(numbers);
console.log(shuffled); // Random order like [3, 1, 5, 2, 4]
console.log(numbers); // [1, 2, 3, 4, 5] (original unchanged)