2024-05

include/advent_utility.h

@@ -9,13 +9,19 @@
 #define MIN(x, y) (x) < (y) ? (x) : (y)
 
 char *md5_str(const char *);
-
 Vector *string_to_int_vector(const char *input_string, const char *delim);
-
 int int_comp(const void *a, const void *b);
-
 char **get_matches(char *in, char *pat, size_t *sz, size_t max_matches);
-
 void free_matches(char **matches, size_t sz);
 
+enum Direction {
+    DIR_NORTH = 0,
+    DIR_EAST = 1,
+    DIR_SOUTH = 2,
+    DIR_WEST = 3,
+};
+
+void turn_right(enum Direction *d);
+void turn_left(enum Direction *d);
+
 #endif

src/2024/05.c

@@ -1,10 +1,94 @@
+#include <limits.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 
 #include "lfinput.h"
 
-void advent2024day05(void) {
-  char *input = get_input("input/2024/05");
-  printf("Solution for Day 05 of 2024 is not completed yet\n");
-  free(input);
+#define RULES_SZ 1176
+
+struct Rule {
+    int a;
+    int b;
+};
+
+static int part_one(int *pages, size_t sz, struct Rule *rules) {
+    int midpoint = pages[sz / 2];
+
+    for (size_t ridx = 0; ridx < RULES_SZ; ++ridx) {
+        int a = -1;
+        int b = 500;
+
+        for (int pidx = 0; pidx < sz; ++pidx) {
+            if (pages[pidx] == rules[ridx].a) {
+                a = pidx;
+            }
+            if (pages[pidx] == rules[ridx].b) {
+                b = pidx;
+            }
+            if (a > b) {
+                midpoint = 0;
+            }
+        }
+    }
+    return midpoint;
+}
+
+int rule_matrix[100][100] = {0};
+
+static int sort(const void *a, const void *b) {
+    int ia = *(int*)a;
+    int ib = *(int*)b;
+    if (rule_matrix[ia][ib]) {
+        return -1;
+    }
+    if (rule_matrix[ib][ia]) {
+        return 1;
+    }
+    return 0;
+}
+
+static int part_two(int *pages, size_t sz, struct Rule *rules) {
+    int s = 0;
+    int sorted[100];
+    memcpy(sorted, pages, sizeof(int) * sz);
+    qsort(sorted, sz, sizeof(int), sort);
+    if (memcmp(pages, sorted, sz * sizeof(int)) != 0) {
+        s += sorted[sz / 2];
+    }
+    return s;
+}
+
+void advent2024day05(void) {
+    size_t sz = 0;
+    char **input = get_lines("input/2024/05", &sz);
+    char *errstr = NULL;
+    struct Rule rules[RULES_SZ];
+    int p1 = 0, p2 = 0;
+
+    size_t i = 0;
+    for (; strlen(input[i]) == 5; ++i) {
+        sscanf(input[i], "%d|%d", &rules[i].a, &rules[i].b);
+        rule_matrix[rules[i].a][rules[i].b] = 1;
+    }
+
+    for (; i < sz; ++i) {
+        size_t sz_sp = 0;
+        char **sp = split(input[i], &sz_sp, ",");
+        int *pages = malloc(sizeof(int) * sz_sp);
+        for (size_t j = 0; j < sz_sp; ++j) {
+            pages[j] = (int) strtonum(sp[j], INT_MIN, INT_MAX, &errstr);
+        }
+
+        p1 += part_one(pages, sz_sp, rules);
+        p2 += part_two(pages, sz_sp, rules);
+
+        free(pages);
+        free(sp);
+    }
+
+    printf("%d\n", p1);
+    printf("%d\n", p2);
+
+    del_lines(input);
 }

src/advent_utility.c

@@ -168,3 +168,11 @@ void free_matches(char **matches, size_t sz) {
     }
     free(matches);
 }
+
+void turn_right(enum Direction *d) {
+    *d = *d == DIR_WEST ? DIR_NORTH : *d + 1;
+}
+
+void turn_left(enum Direction *d) {
+    *d = *d == DIR_NORTH ? DIR_WEST : *d - 1;
+}