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Yup. This is one way to do it:

http :/ / en.wikipedia.org/wiki/Fisher%E2%80%93Yates_shuffle

Hi,

The right way to do it : Space complexity : O(1), Time Complexity : O(n)

#include <stdio.h>
#include <conio.h>
#include <stdlib.h>

#define CARD_COUNT 52

void swap(int *card_arr, int index1, int index2)
{
	if(index1 != index2)
	{
		card_arr[index1] = card_arr[index1] + card_arr[index2];
		card_arr[index2] = card_arr[index1] - card_arr[index2];
		card_arr[index1] = card_arr[index1] - card_arr[index2];
	}
}

int main(void)
{
	int i;

	int card_arr[CARD_COUNT] = {0};

	for(i = 0; i < CARD_COUNT; i++)
		card_arr[i] = i+1;
	
	for(i = 0; i < CARD_COUNT; i++)
	{
		int index = rand() % (CARD_COUNT - i) + i;
		swap( card_arr, i, index);
	}

	getch();
}

for i = 0 to 51
    generate a random number in the range (i+1 to 51): @next_idx
    swap the elements at the indices i and next_idx

srand((unsigned)time(0))
for(i=0;i<=51;i++)
{
n=rand()%52;
swap(a[i],a[n])
}

}

#include<stdio.h>
#include<stdlib.h>
#include<time.h>
main()
{
int card[52];
int n;
int i,c;

srand(time(NULL)); // initialize the seed randomly

printf("How many card you want to open from the deck after shuffle");
scanf("%d",&n);

for (i=0; i<52; i++)
{
card[i] = i; // fill the array in order
}

//--- Shuffle elements by randomly exchanging each with one other.
for (i=0; i<(52-1); i++)
{
int r = i + (rand() % (52-i)); // Random remaining position.
printf("rand()%(52-i):%d\n",r);
int temp = card[i];
card[i] = card[r];
card[r] = temp;
}

//--- Print first n cards as ints.
for (c=0; c<n; c++)
{
printf("%d ",card[c]);
}

getch();
}

Generate the Random No. Between 0-51(eg. x and y)....select this card and put it at the top, now generate the Random no between x-y ..so on until both no get equal..
Repeat this process n time (Depend upon the your choice of shuffle )

-- you can do it with divide and conquer technique ...
-- In the merging , instead of normal mearging ... you include your own merging procedure(which will take 1 element from first array and another from the second array ..)
so final array will shuffled randomly ...