2016/advent6.c

   1 #define _GNU_SOURCE 1
   2 #include <stdio.h>
   3 #include <string.h>
   4 #include <stdlib.h>
   5 #include <unistd.h>
   6 #include <stdbool.h>
   7 #include <ctype.h>
   8
   9 unsigned int grid[8][26];
  10
  11 int main(int argc, char **argv)
  12 {
  13   int count = -1;
  14   int limit = 8;
  15   if (argc == 2) {
  16     limit = atoi (argv[1]);
  17     if (limit > 8)
  18       return 1;
  19   }
  20   int c = '\n';
  21   while (c == '\n') {
  22     count++;
  23     for (int i = 0; i < limit; i++) {
  24       if ((c = getchar ()) < 0)
  25         break;
  26       grid[i][c - 'a']++;
  27     }
  28     c = getchar ();
  29   }
  30   printf ("after reading %d repetitions, message was: ", count);
  31   for (int i = 0; i < limit; i++) {
  32     int min = 0;
  33     int j;
  34     for (j = 0; j < 26; j++)
  35       if (grid[i][j] - 1 < grid[i][min] - 1)
  36         min = j;
  37     putchar (min + 'a');
  38   }
  39   putchar ('\n');
  40   return 0;
  41 }