aoc

Advent of Code challenges
log files refs
aoc_2023_1_2.c (1477B)
      1#include <stdio.h>
      2#include <stdlib.h>
      3#include <string.h>
      4#include <ctype.h>
      5
      6#define NELEMS(x) (int) (sizeof(x) / sizeof((x)[0]))
      7#define MAX_DIGITS 100
      8
      9typedef struct {
     10  int count;
     11  char digits[MAX_DIGITS];
     12} line_t;
     13
     14const char *DIGITS[9] = { "one", "two", "three", "four", "five", "six", "seven", "eight", "nine" };
     15
     16long perform(char *data) {
     17  (void) data;
     18  int len = strlen(data);
     19  int size = 0;
     20  for (int i = 0; i < len; i++) {
     21    char c = data[i];
     22    if (c == '\n') {
     23      size++;
     24    }
     25  }
     26  int idx = 0;
     27  line_t lines[size];
     28  lines[idx] = (line_t) { 0, {0} };
     29  for (int i = 0; i < len; i++) {
     30    char c = data[i];
     31    if (isdigit(c)) {
     32      line_t *line = &lines[idx];
     33      line->digits[line->count++] = c;
     34    }
     35    for (int j = 0; j < NELEMS(DIGITS); j++) {
     36      const char *digit = DIGITS[j];
     37      int digit_len = strlen(digit);
     38      if (strncmp(data + i, digit, digit_len) == 0) {
     39        line_t *line = &lines[idx];
     40        line->digits[line->count++] = '1' + j;
     41        break;
     42      }
     43    }
     44    if (c == '\n') {
     45      idx++;
     46      lines[idx] = (line_t) { 0, {0} };
     47    }
     48  }
     49  int sum = 0;
     50  for (int i = 0; i < idx; i++) {
     51    line_t *line = &lines[i];
     52    if (line->count == 0) {
     53      continue;
     54    }
     55    char set = line->digits[0];
     56    char end = set;
     57    if (line->count > 1) {
     58      end = line->digits[line->count - 1];
     59    }
     60    char str[2] = { set, end };
     61    int digit = strtol(str, NULL, 10);
     62    sum += digit;
     63  }
     64  return sum;
     65}