Shuffle: Fisher-Yates Card Deck Shuffling Algorithm (CTCI 17.2)

TL;DR

• The Problem: CTCI problem 17.2 technical mechanics.
• The Approach: CTCI problem 17.2: shuffle a deck of cards uniformly using the Fisher-Yates (Knuth) in-place algorithm.
• Complexity: Optimal Time and Memory bounds.

This article provides a clear breakdown of CTCI problem 17.2.

1. Context and Problem Statement

CTCI problem 17.2: shuffle a deck of cards uniformly using the Fisher-Yates (Knuth) in-place algorithm.

2. Technical Code & Mechanics

public static void shuffleArray(int[] cards) {
    Random rand = new Random();
    for (int i = 0; i < cards.length; i++) {
        int k = rand.nextInt(i + 1);
        int temp = cards[i];
        cards[i] = cards[k];
        cards[k] = temp;
    }
}

3. Key Takeaways and Edge Cases

Always test boundary conditions and invalid input states.