university/S1/GdCP/aoc22.c

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

void mix(long *n, long r) { *n = *n ^ r; }
void prune(long *n) { *n = *n % 16777216; }

int main() {
  FILE *file = fopen("22.in", "r");
  if (!file) {
    perror("Unable to open file");
    return 1;
  }

  int *array = malloc(10 * sizeof(int));
  if (!array) {
    perror("Memory allocation failed");
    fclose(file);
    return 1;
  }

  int num, size = 0, capacity = 10;
  while (fscanf(file, "%d", &num) == 1) {
    if (size == capacity) {
      capacity *= 2;
      array = realloc(array, capacity * sizeof(int));
      if (!array) {
        perror("Memory allocation failed");
        fclose(file);
        return 1;
      }
    }
    array[size++] = num;
  }

  fclose(file);

  long r, r1, r2, r3 = 0;
  for (int i = 0; i < size; i++) {
    long n = array[i];
    for (int s = 0; s < 2000; s++) {
      r1 = n * 64;
      mix(&n, r1);
      prune(&n);

      r2 = floor(n / 32.0);
      mix(&n, r2);
      prune(&n);

      r3 = n * 2048;
      mix(&n, r3);
      prune(&n);
    }
    r += n;
  }
  printf("%li\n", r);

  free(array);
  return 0;
}