adventofcode2025/adventofcodeday4.c at main · pPyrius/adventofcode2025 · GitHub

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

typedef struct {
  char *lines[3];
  int sum;
} forklifts_management;

void init(forklifts_management *forklifts) {
  forklifts->sum = 0;
  forklifts->lines[0] = malloc(500);
  forklifts->lines[1] = malloc(500);
  forklifts->lines[2] = malloc(500);
}

void shift_lines(forklifts_management *forklifts) {
  memset(forklifts->lines[0], '\0', 500);
  memcpy(forklifts->lines[0], forklifts->lines[1], 500);
  memset(forklifts->lines[1], '\0', 500);
  memcpy(forklifts->lines[1], forklifts->lines[2], 500);
  memset(forklifts->lines[2], '\0', 500);
}
int sum_paper(forklifts_management *forklifts, int i) {
  int sum = 0;
  if (i != 0) {
    if (forklifts->lines[0][i - 1] == 64) {
      sum++;
    }
    if (forklifts->lines[1][i - 1] == 64) {
      sum++;
    }
    if (forklifts->lines[2][i - 1] == 64) {
      sum++;
    }
  }
  if (forklifts->lines[0][i] == 64) {
    sum++;
  }
  if (forklifts->lines[2][i] == 64) {
    sum++;
  }
  if (i != strlen(forklifts->lines[1]) - 1) {
    if (forklifts->lines[0][i + 1] == 64) {
      sum++;
    }
    if (forklifts->lines[1][i + 1] == 64) {
      sum++;
    }
    if (forklifts->lines[2][i + 1] == 64) {
      sum++;
    }
  }
  return sum < 4;
}

void count_paper(forklifts_management *forklifts) {
  for (int i = 0; i < strlen(forklifts->lines[1]); i++) {
    if (forklifts->lines[1][i] == 64) {
      forklifts->sum += sum_paper(forklifts, i);
    }
  }
}

int main(void) {
  forklifts_management *forklifts = malloc(sizeof(forklifts_management));
  init(forklifts);

  FILE *file = fopen("input", "r");
  fscanf(file, "%s", forklifts->lines[2]);
  do {
    shift_lines(forklifts);
    fscanf(file, "%s", forklifts->lines[2]);
    count_paper(forklifts);
  } while ((forklifts->lines[0][0] != '\0') + (forklifts->lines[1][0] != '\0') +
               (forklifts->lines[2][0] != '\0') >
           1);
  printf("Sum is: %d\n", forklifts->sum);
}