C Fun C Challenge(Pointers, Random Integers, Arrays)

[C] Fun C Challenge(Pointers, Random Integers, Arrays) - Printable Version

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Fun C Challenge(Pointers, Random Integers, Arrays) - EmacsSucksButILikeIt - Feb 17, 2022

Fun C Challenge(Pointers, Random Integers, Arrays)..

Here's a fun and standard C problem. Can you shuffle an array of integers via an array of int pointers?

I.E.

Say you have an array of integers:

Code 
#define ARR_SIZE 10

int arr[ARR_SIZE] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};

and an array of int pointers:

Code 
#define ARR_SIZE 10

int *arr_ptrs[ARR_SIZE] = {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL};

Now can you use the addresses of the elements in arr to populate arr_ptrs such that each address in arr is present in arr_ptrs only once and is shuffled.

Here's something to get you started:

Code 
#include <stdio.h>

#include <stdlib.h>

#include <time.h>

#define ARR_SIZE 10

void shuffle(int arr[], int *arr_ptr[], size_t size) {

  //Do your C magic here

}

int main(int argc, char **argv) {

  size_t i = 0;

  int arr[ARR_SIZE] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};

  int *arr_ptrs[ARR_SIZE] = {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL};

  shuffle(arr, arr_ptrs, ARR_SIZE);

  for (; i < ARR_SIZE; i++) {

    arr_ptrs[i] ?

      fprintf(stdout, "(%ld): %d\n", i, *arr_ptrs[i]) :

      fprintf(stdout, "(%ld): NULL value\n", i);

  }

  return 0;

}

Here is some examples of what the output of printing arr_ptrs would look like.

Code 
(0): 8

(1): 7

(2): 2

(3): 3

(4): 10

(5): 1

(6): 9

(7): 4

(8): 5

(9): 6

Code 
(0): 1

(1): 3

(2): 8

(3): 7

(4): 4

(5): 10

(6): 2

(7): 6

(8): 5

(9): 9

Notice that each number from arr is represented and the output is shuffled.

RE: Fun C Challenge(Pointers, Random Integers, Arrays) - unazed - Jun 4, 2022

a simple xorshift prng on the indices should be fine