adventofcodeday3.c

#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>

typedef struct {
  char *joltage;
  ulong joltage_sum;
} battery_banks;

void maximize_joltage(battery_banks *battery_banks) {
  int imax[2][2] = {{0, 0}, {0, 0}};

  for (int i = 0; i < strlen(battery_banks->joltage); i++) {
    if (imax[0][0] < battery_banks->joltage[i] &&
        i != strlen(battery_banks->joltage) - 1) {
      imax[0][0] = battery_banks->joltage[i];
      imax[0][1] = i;
    }
  }

  for (int i = imax[0][1] + 1; i < strlen(battery_banks->joltage); i++) {
    if (imax[1][0] < battery_banks->joltage[i]) {
      imax[1][0] = battery_banks->joltage[i];
      imax[1][1] = i;
    }
  }
  char *joltage_max = malloc(2);
  joltage_max[0] = imax[0][0];
  joltage_max[1] = imax[1][0];
  battery_banks->joltage_sum += strtoul(joltage_max, NULL, 10);
  free(joltage_max);
}

int main(void) {
  battery_banks *battery_banks = malloc(sizeof(*battery_banks));
  battery_banks->joltage_sum = 0;
  battery_banks->joltage = malloc(500);

  FILE *file = fopen("input", "r");
  while (fscanf(file, "%s", battery_banks->joltage) != EOF) {
    maximize_joltage(battery_banks);
  }
  printf("Sum is : %lu\n", battery_banks->joltage_sum);
  fclose(file);
}