zalupa

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

int main(void) {
    int n, prev_size = 4;
    int added[4] = {1,3,7,9};
    int value, root = 4;
    int *prev = malloc(prev_size * sizeof(int));
    prev[0] = 2; prev[1] = 3; prev[2] = 5; prev[3] = 7;
    int *arr = malloc(4 * prev_size * sizeof(int));
    scanf("%d", &n);
    int pos = 0, size = 1;
    int *new_arr = malloc(size*sizeof(int));
    if (n==1){
        for (int i=0;i<4;++i){
            printf("%d ", prev[i]);
        }
    }
    else {
        for (int i = 0; i < n - 1; ++i) {
            pos = 0;
            size = 1;
            new_arr = realloc(new_arr, size * sizeof(int));
            printf("%lu\n", 4 * prev_size * sizeof(int));
            arr = realloc(arr, 4 * prev_size * sizeof(int));
            printf("prev_size = %d\n", prev_size);
            for (int k=0; k<prev_size; ++k){
                printf("%d ", prev[k]);
            }
            printf("\n");
            for (int j = 0; j < prev_size; ++j) {
                for (int k = 0; k < 4; ++k) {
                    value = prev[j] * 10 + added[k];
                    printf("%d - %d; ", value, prev[j]);
                    arr[j * 4 + k] = value;
                }
            }
            printf("\n");
            for (int j = 0; j < 4 * prev_size; ++j) {
                while (root * root <= arr[j]) {
                    ++root;
                }
                int res = 1;
                for (int k = 3; k < root; ++k) { // n != 1
                    if (!(arr[j] % k)) {
                        res = 0;
                        break;
                    }
                }
                if (res) {
                    if (pos == size) {
                        size *= 2;
                        new_arr = realloc(new_arr, size * sizeof(int));
                    }
                    new_arr[pos] = arr[j];
                    ++pos;
                }
            }
            prev_size = pos;
            free(prev);
            prev = malloc(prev_size);

            for (int j = 0; j < pos; ++j) {
                prev[j] = new_arr[j];
            }
            printf("new_array:\n");
            for (int k = 0; k < pos; ++k) {
                printf("%d ", new_arr[k]);
            }
            printf("\nprev_copy:\n");
            for (int k = 0; k < pos; ++k) {
                printf("%d ", prev[k]);
            }
            printf("\n");
        }
        for (int i = 0; i < pos; ++i) {
            printf("%d ", new_arr[i]);
        }
    }
    free(prev);
    free(arr);
    free(new_arr);
}