Shuffling a deck of cards

Question

I'm making a Deck class for a C++ program. It needs to have two methods: one to pop a card off the top of the deck, another to shuffle the deck. I'm concerned with the latter.

Cards are represented as integers 1 to 52 inclusive. What is the fastest algorithm to shuffle the deck (assuming a 'good' level of randomness)?

Answer 1

If you wish to implement the shuffle yourself, a very straightforward but also functional shuffling algorithm: Fisher–Yates shuffle.

To shuffle an array a of n elements:

for i from n − 1 downto 1 do
   j ← random integer with 0 ≤ j ≤ i
   exchange a[j] and a[i]

Of course, the C++ standard library also has things like this implemented for you, such as std::random_shuffle, included via the <algorithm> header.