Storing arrays into new arrays - arrays

Question

I am not very good with words so I included a visual sample of my code. I would appreciate the help. Thank you (To add I am also a fresh programmer trying to learn algorithms but im struggling on this one)
Is there a working way to store a 2d array into a 1D array?? I have tried to do it in this way but I'm getting garbage values instead when I print it out.
#include <stdio.h>
int main() {
int disp[4][4] = {{12, 14, 32, 9},
{19, 24, 3, 4},
{11, 26, 3, 8},
{13, 24, 7, 5}
};
int quadrant_size = 2;
int k = 0;
int flat[4] = {0};
int N = 4;
int x, y, i, j;
for (x = 0 ; x < N ; x += quadrant_size) {
for (y = 0 ; y < N ; y += quadrant_size) {
int mx = disp[x][y];
for (i = x ; i < x + quadrant_size ; i++) {
for (j = y ; j < y + quadrant_size ; j++) {
if (disp[i][j] > mx) {
mx = disp[i][j];
flat[k] = disp[i][j];
k++;
}
}
}
printf("%d ", mx);
}
printf("\n");
}
for (i = 0; i < 4; i++) {
printf("%d", flat[i]);
}
return 0;
}
Basically, the output of this program will give you a result of
24 32
26 8
I am trying to print this in a 1D array using flat[k] running through a for loop will generate (Code sample included) without the pattern shown above. However, I am getting random values instead of getting a result of (When converting 2D Arrays to a 1D array)
Should be: 24 32 26 8
Instead, I am getting: 141924268
Is there an efficient way of executing this?

Answer 1

I made a few changes to the code and marked them with comments.
The essential problem was that writing the maximum to the array (and incrementing its write index) was inside the loop for determining the max element.
In your code you added each 'increment' to the array and not the final value as intended.
Also note, that there is no bounds check on k. So it might overflow the flat-array. It might be a good idea to add that if you use this code on other matrix sizes as well.
#include <stdio.h>
int main() {
int disp[4][4] = {
{12, 14, 32, 9},
{19, 24, 3, 4},
{11, 26, 3, 8},
{13, 24, 7, 5}
};
int quadrant_size = 2;
int k = 0;
int flat[4] = {0};
int N = 4;
int x, y, i, j;
for (x = 0 ; x < N ; x += quadrant_size) {
for (y = 0 ; y < N ; y += quadrant_size) {
int mx = disp[x][y];
for (i = x ; i < N && i < x + quadrant_size ; i++) {
// ~~~~~~~~ additional bounds check
for (j = y ; j < N && j < y + quadrant_size ; j++) {
// ~~~~~~~~ additional bounds check
if (disp[i][j] > mx) {
mx = disp[i][j];
// removed code here
}
}
}
// move code here
// only accept the maximum
flat[k] = mx;
k++;
printf("%d ", mx);
}
printf("\n");
}
for (i = 0; i < k; i++) {
// ~ use k as bound, k knows how many elements where inserted
printf("%d ", flat[i]);
// ~ space for readability
}
return 0;
}