Write a program to shuffle a deck of cards.

Solution #1: The approach is to pick a card in sequence and replace it with another card picked at random from the remaining cards. Here is the code,

#include 
#include 
#include 

#define DECK_SIZE 52

//generate random number between a and b(both inclusive)
int gen_rand(int a, int b)
{
    int num;

    srand(time(NULL));

    num = a + rand()%(b-a+1);

    return num;
}

void shuffle(int *deck, int size)
{
    int i=0;
    int rand_pick=0;
    int temp=0;

    for(i=0; i < size; i++)
    {
        //pick a random card between current card and last card(both inclusive)
        rand_pick = gen_rand(i, size);

        //swap it with the current card
        int temp = deck[rand_pick];
        deck[rand_pick] = deck[i];
        deck[i] = temp;
    }
}

int main()
{
    int deck[DECK_SIZE];

    //initalize cards in serial order
    int i=0;
    for(i=0; i < DECK_SIZE; i++)
        deck[i] = i;

    shuffle(deck, DECK_SIZE);

    //print cards
    for(i=0; i < DECK_SIZE; i++)
        printf("%d\n", deck[i]);

    return 0;
}