aoc-2019/day4/1/secure_container.c

#include "neat_macro.h"

int p_six_digit(char* s) {
  int counter = 0;
  for(char* c=s; *c!='\0'; c++) {
    counter++;
  }

  return (counter == 6);
}

int p_double(char *s) {
  char last_char = '\0';
  for (char *c = s; *c!='\0'; c++) {
    if(last_char == *c) return 1;
    last_char = *c;
  }

  return 0;
}

int p_decrease(char *s) {
  char last_char = '\0';
  for (char *c = s; *c!='\0'; c++) {
    if ((last_char - '0') > (*c - '0')) return 0;
    last_char = *c;
  }

  return 1;
}

int main(int argc, char **argv) {
  int start = atoi(argv[1]);
  int end = atoi(argv[2]);

  int count = 0;
  for(int i=start; i<end; i++){
    char buf[7];
    snprintf(buf, 7, "%d", i);

    if ((i % 100000)==0) {
       log("At %d/%d %f%%\n", i, end, (((double)i) / end) * 100);
       log("At %s\n", buf);
    }

    if(p_six_digit(buf) && p_double(buf) && p_decrease(buf)){
      count++;
    }
  }

  printf("Numbers: %d\n", count);
}