aoc

Advent of Code challenges
log files refs
aoc_2024_1_1.c (887B)
      1#include <stdlib.h>
      2#include <string.h>
      3#include <ctype.h>
      4
      5int compare_num(const void *a, const void *b) {
      6  return (*(int *) a) - (*(int *) b);
      7}
      8
      9long perform(char *data) {
     10  int len = strlen(data);
     11  int size = 0;
     12  for (int i = 0; i < len; i++) {
     13    char c = data[i];
     14    if (c == '\n') {
     15      size++;
     16    }
     17  }
     18  int lft[size];
     19  int rgt[size];
     20  int odd = 0;
     21  int ln = 0;
     22  for (int i = 0; i < len;) {
     23    char c = data[i];
     24    if (isdigit(c)) {
     25      char *end = NULL;
     26      int num = strtol(data + i, &end, 10);
     27      odd ? (rgt[ln] = num) : (lft[ln] = num);
     28      odd = !odd;
     29      i += end - (data + i);
     30      continue;
     31    }
     32    if (c == '\n') {
     33      ln++;
     34    }
     35    i++;
     36  }
     37  qsort(lft, size, sizeof(int), compare_num);
     38  qsort(rgt, size, sizeof(int), compare_num);
     39  int sum = 0;
     40  for (int i = 0; i < size; i++) {
     41    sum += abs(lft[i] - rgt[i]);
     42  }
     43  return sum;
     44}