2024-06,07

.gitmodules

@@ -1,6 +1,6 @@
 [submodule "lib/libflint"]
 	path = lib/libflint
-	url = https://git.burkey.co/eburk/libflint
+	url = https://gitlab.com/eburk/libflint.git
 [submodule "lib/uthash"]
 	path = lib/uthash
 	url = https://github.com/troydhanson/uthash

CMakeLists.txt

@@ -17,24 +17,38 @@ file(GLOB SRC2020 src/2020/*.c)
 file(GLOB SRC2021 src/2021/*.c)
 file(GLOB SRC2022 src/2022/*.c)
 file(GLOB SRC2023 src/2023/*.c)
+file(GLOB SRC2024 src/2024/*.c)
 
 file(COPY input DESTINATION ${CMAKE_BINARY_DIR})
 
-add_executable(advent ${SRC} ${SRC2015} ${SRC2016} ${SRC2017} ${SRC2018} ${SRC2019} ${SRC2020} ${SRC2021} ${SRC2022} ${SRC2023})
+add_executable(advent ${SRC} ${SRC2015} ${SRC2016} ${SRC2017} ${SRC2018} ${SRC2019} ${SRC2020} ${SRC2021} ${SRC2022} ${SRC2023} ${SRC2024})
+
+set(INCLUDES
+	include
+	lib/libflint/include
+	lib/uthash/src
+)
 
 if ((${CMAKE_SYSTEM_NAME} STREQUAL "OpenBSD"))
-	target_link_libraries(advent PRIVATE flint)
+	find_package(PCRE2 REQUIRED)
-	target_include_directories(advent PRIVATE include lib/libflint/include lib/uthash/src)
+	target_include_directories(advent PRIVATE ${INCLUDES} ${PCRE2_INCLUDE_DIR})
+	target_link_libraries(advent PRIVATE flint ${PCRE2_LIBRARIES})
 elseif ((${CMAKE_SYSTEM_NAME} STREQUAL "Linux"))
 	find_package(OpenSSL REQUIRED)
-	target_link_libraries(advent PRIVATE bsd flint ${OPENSSL_LIBRARIES})
+	target_include_directories(advent PRIVATE ${INCLUDES} ${OpenSSL_INCLUDE_DIR} ${PCRE2_INCLUDE_DIR})
-	target_include_directories(advent PRIVATE include lib/libflint/include lib/uthash/src ${OpenSSL_INCLUDE_DIR})
+	target_link_libraries(advent PRIVATE bsd flint ${PCRE2_LIBRARIES} ${OPENSSL_LIBRARIES})
 elseif ((${CMAKE_SYSTEM_NAME} STREQUAL "Darwin"))
+	# OpenSSL
 	set(OPENSSL_ROOT_DIR /opt/homebrew/opt/openssl@3)
 	set(OpenSSL_INCLUDE_DIR /opt/homebrew/opt/openssl@3/include)
 	find_package(OpenSSL REQUIRED)
-	target_link_libraries(advent PRIVATE flint ${OPENSSL_LIBRARIES})
+
-	target_include_directories(advent PRIVATE include lib/libflint/include lib/uthash/src ${OpenSSL_INCLUDE_DIR})
+	# PCRE2
+	set(PCRE2_INCLUDE_DIR /opt/homebrew/opt/pcre2/include)
+	set(PCRE2_LIBRARIES /opt/homebrew/opt/pcre2/lib/libpcre2-8.dylib)
+
+	target_include_directories(advent PRIVATE ${INCLUDES} ${OpenSSL_INCLUDE_DIR} ${PCRE2_INCLUDE_DIR})
+	target_link_libraries(advent PRIVATE flint ${OPENSSL_LIBRARIES} ${PCRE2_LIBRARIES})
 else()
   message(FATAL_ERROR "OS ${CMAKE_SYSTEM_NAME} is not supported" )
 endif()

README.md

@@ -6,7 +6,7 @@ Advent Of Code solutions using C99. Builds and runs on macOS, Linux, and OpenBSD
 
 Be sure to clone the project with its submodules:
 
-    git clone --recurse-submodules https://git.burkey.co/eburk/advent
+    git clone --recurse-submodules https://gitlab.com/eburk/aoc
 
 This project relies on several BSD extensions to the stdlib. OpenBSD and macOS users should be able to build the project out of the box. Linux users will need `libbsd` installed. The package is called `libbsd-dev` on Debian-based systems.
 

generator.sh

@@ -2,7 +2,7 @@
 
 mkdir -p include
 
-for year in {2023..2023}; do
+for year in {2015..2024}; do
   rm -rf "src/${year}"
   mkdir -p "src/${year}"
 

get_input.sh

@@ -4,8 +4,21 @@ get(){
 		curl -s --cookie "session=$1" "$2" | perl -pe 'chomp if eof' > "$3"
 }
 
-rm -rf input
+if [ -n "${2+x}" ] && [ -n "${3+x}" ]; then
-for year in {2015..2023}; do
+  year="20$2"
+  day="$3"
+	if [ "$day" -lt 10 ]; then
+	  d="0$day"
+	else
+		d="$day"
+	fi
+	url="https://adventofcode.com/$year/day/$day/input"
+	get "$1" "$url" "input/$year/$d"
+  exit 0
+fi
+
+#rm -rf input
+for year in {2015..2024}; do
 	mkdir -p input/"$year"
 	for day in {1..25}; do
 		if [[ day -lt 10 ]]; then

include/advent2024.h

@@ -0,0 +1,58 @@
+#ifndef ADVENT_2024_H
+#define ADVENT_2024_H
+
+void advent2024day01(void);
+void advent2024day02(void);
+void advent2024day03(void);
+void advent2024day04(void);
+void advent2024day05(void);
+void advent2024day06(void);
+void advent2024day07(void);
+void advent2024day08(void);
+void advent2024day09(void);
+void advent2024day10(void);
+void advent2024day11(void);
+void advent2024day12(void);
+void advent2024day13(void);
+void advent2024day14(void);
+void advent2024day15(void);
+void advent2024day16(void);
+void advent2024day17(void);
+void advent2024day18(void);
+void advent2024day19(void);
+void advent2024day20(void);
+void advent2024day21(void);
+void advent2024day22(void);
+void advent2024day23(void);
+void advent2024day24(void);
+void advent2024day25(void);
+
+void (*solutions2024[25])(void) = {
+  advent2024day01,
+  advent2024day02,
+  advent2024day03,
+  advent2024day04,
+  advent2024day05,
+  advent2024day06,
+  advent2024day07,
+  advent2024day08,
+  advent2024day09,
+  advent2024day10,
+  advent2024day11,
+  advent2024day12,
+  advent2024day13,
+  advent2024day14,
+  advent2024day15,
+  advent2024day16,
+  advent2024day17,
+  advent2024day18,
+  advent2024day19,
+  advent2024day20,
+  advent2024day21,
+  advent2024day22,
+  advent2024day23,
+  advent2024day24,
+  advent2024day25
+};
+
+#endif

include/advent_utility.h

@@ -9,7 +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

lib/uthash

@@ -1 +1 @@
-Subproject commit 619fe95ca4679249528f086536aadd0c469dbd99
+Subproject commit f69112c04f1b6e059b8071cb391a1fcc83791a00

src/2015/05.c

@@ -1,13 +1,13 @@
 #include <stdio.h>
 #include <stdlib.h>
 
-#include "advent_utility.h"
+#include <lfinput.h>
 
 void advent2015day05(void) {
     /* Sometimes, grep really is the best tool */
-    char *p1 = capture_system(
+    const char *p1 = capture_system(
-            "grep -E \"(.*[aeiou]){3}\" ./input/2015/05 | grep \"\\(.\\)\\1\" | egrep -v \"(ab|cd|pq|xy)\" | wc -l");
+            "grep -E \"(.*[aeiou]){3}\" ./input/2015/05 | grep \"\\(.\\)\\1\" | egrep -v \"(ab|cd|pq|xy)\" | wc -l", 0);
-    char *p2 = capture_system("grep \"\\(..\\).*\\1\" ./input/2015/05 | grep \"\\(.\\).\\1\" | wc -l");
+    const char *p2 = capture_system("grep \"\\(..\\).*\\1\" ./input/2015/05 | grep \"\\(.\\).\\1\" | wc -l", 0);
 
     printf("%s%s", p1, p2);
 

src/2024/01.c

@@ -0,0 +1,58 @@
+#include <limits.h>
+#include <stdio.h>
+
+#include "lfinput.h"
+#include "advent_utility.h"
+
+void advent2024day01(void) {
+    size_t sz = 0;
+    char **input = get_lines("input/2024/01", &sz);
+    int a[sz];
+    int b[sz];
+    const char *errstr;
+
+    for (size_t i = 0; i < sz; i++) {
+        size_t sp_sz = 0;
+        char **sp = split(input[i], &sp_sz, "   ");
+
+        a[i] = (int) strtonum(sp[0], INT_MIN, INT_MAX, &errstr);
+        if (errstr != NULL) {
+            printf("ERR: %s\n", errstr);
+            free(sp);
+            break;
+        }
+
+        b[i] = (int) strtonum(sp[1], INT_MIN, INT_MAX, &errstr);
+        if (errstr != NULL) {
+            printf("ERR: %s\n", errstr);
+            free(sp);
+            break;
+        }
+        free(sp);
+    }
+
+    qsort(a, sz, sizeof(int), int_comp);
+    qsort(b, sz, sizeof(int), int_comp);
+
+    int p1 = 0;
+    for (size_t i = 0; i < sz; i++) {
+        p1 += abs(a[i] - b[i]);
+    }
+
+    printf("%d\n", p1);
+
+    int p2 = 0;
+    for (size_t i = 0; i < sz; i++) {
+        int c = 0;
+        for (size_t j = 0; j < sz; j++) {
+            if (a[i] == b[j]) {
+                ++c;
+            }
+        }
+        p2 += a[i] * c;
+    }
+
+    printf("%d\n", p2);
+
+    del_lines(input);
+}

src/2024/02.c

@@ -0,0 +1,116 @@
+#include <lflinkedlist.h>
+#include <lfmemory.h>
+#include <limits.h>
+#include <stdio.h>
+
+#include "lfinput.h"
+#include "lfbool.h"
+
+static int part1(List *a) {
+    ListNode *n = a->head;
+
+    int inc = LFFALSE;
+    if (*(int *) n->data < *(int *) n->next->data) {
+        inc = LFTRUE;
+    }
+
+    int safe = LFTRUE;
+    while (n->next != NULL) {
+        int prev = *(int *) n->data, cur = *(int *) n->next->data;
+        if (inc == LFTRUE) {
+            if (prev > cur || prev == cur || cur - prev > 3) {
+                safe = LFFALSE;
+                break;
+            }
+        } else {
+            if (prev < cur || prev == cur || prev - cur > 3) {
+                safe = LFFALSE;
+                break;
+            }
+        }
+        n = n->next;
+    }
+
+    return safe;
+}
+
+static int part2(List *a) {
+    ListNode *n = a->head;
+
+    int inc = LFFALSE;
+    if (*(int *) n->data < *(int *) n->next->data) {
+        inc = LFTRUE;
+    }
+    int bad = 0;
+
+    int safe = LFTRUE;
+    while (n->next != NULL) {
+        const int prev = *(int *) n->data;
+        const int cur = *(int *) n->next->data;
+        if (inc == LFTRUE) {
+            if (prev > cur || prev == cur || cur - prev > 3) {
+                if (bad == 0) {
+                    void *t;
+                    ll_remove_next(a, n, &t);
+                    bad = 1;
+                    continue;
+                }
+                safe = LFFALSE;
+                break;
+            }
+        } else {
+            if (prev < cur || prev == cur || prev - cur > 3) {
+                if (bad == 0) {
+                    void *t;
+                    ll_remove_next(a, n, &t);
+                    bad = 1;
+                    continue;
+                }
+                safe = LFFALSE;
+                break;
+            }
+        }
+        n = n->next;
+    }
+
+    return safe;
+}
+
+void advent2024day02(void) {
+    size_t sz = 0;
+    char **input = get_lines("input/2024/02", &sz);
+    char *errstr = NULL;
+    int p1 = 0, p2 = 0;
+
+    for (size_t i = 0; i < sz; i++) {
+        List *a = malloc(sizeof(List));
+        ll_init(a, NULL);
+        ArenaAllocator *arena = malloc(sizeof(ArenaAllocator));
+        arena_init(arena, sizeof(int) * 32);
+
+        size_t sp_sz = 0;
+        char **sp = split(input[i], &sp_sz, " ");
+
+        for (size_t j = 0; j < sp_sz; j++) {
+            int *t = arena_malloc(arena, sizeof(int));
+            *t = (int) strtonum(sp[j], INT_MIN, INT_MAX, &errstr);
+            if (errstr != NULL) {
+                printf("ERR: %s\n", errstr);
+                exit(1);
+            }
+            ll_ins_next(a, a->tail, t);
+        }
+
+        p1 += part1(a);
+        p2 += part2(a);
+
+        free(sp);
+        ll_destroy(a);
+        arena_free(arena);
+    }
+
+    printf("%d\n", p1);
+    printf("%d\n", p2);
+
+    del_lines(input);
+}

src/2024/03.c

@@ -0,0 +1,34 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "lfinput.h"
+#include "advent_utility.h"
+
+void advent2024day03(void) {
+    char *input = get_input("input/2024/03");
+    size_t m_sz = 0;
+    char **matches = get_matches(input, "mul\\(\\d+,\\d+\\)|do\\(\\)|don't\\(\\)", &m_sz, 32);
+    int p1 = 0, p2 = 0, x, y, enabled = 1;
+
+    for (size_t i = 0; i < m_sz; i++) {
+        if (strcmp(matches[i], "do()") == 0) {
+            enabled = 1;
+        } else if (strcmp(matches[i], "don't()") == 0) {
+            enabled = 0;
+        }
+
+        if (strstr(matches[i], "mul") != NULL) {
+            sscanf(matches[i], "mul(%d,%d)", &x, &y);
+            p1 += x * y;
+            if (enabled) {
+                p2 += x * y;
+            }
+        }
+    }
+
+    printf("%d\n", p1);
+    printf("%d\n", p2);
+
+    free_matches(matches, m_sz);
+    free(input);
+}

src/2024/04.c

@@ -0,0 +1,92 @@
+#include <stdio.h>
+#include <string.h>
+
+#include "lfinput.h"
+
+#define GRID_SZ 140
+char **gd;
+
+static int horz(int x, int y, const char *w) {
+    if (y <= GRID_SZ - 4) {
+        return strncmp(&gd[x][y], w, 4) == 0;
+    }
+    return 0;
+}
+
+static int vert(int x, int y, const char *w) {
+    if (x <= GRID_SZ - 4) {
+        int c = 1;
+        for (int j = 0; j < 4; j++) {
+            if (gd[x + j][y] != w[j]) {
+                c = 0;
+            }
+        }
+        return c;
+    }
+    return 0;
+}
+
+static int diag_right(int x, int y, const char *w) {
+    if (x <= GRID_SZ - 4 && y >= 3) {
+        int c = 1;
+        for (int j = 0; j < 4; j++) {
+            if (gd[x + j][y - j] != w[j]) {
+                c = 0;
+            }
+        }
+        return c;
+    }
+    return 0;
+}
+
+static int diag_left(int x, int y, const char *w) {
+    if (x <= GRID_SZ - 4 && y <= GRID_SZ - 4) {
+        int c = 1;
+        for (int j = 0; j < 4; j++) {
+            if (gd[x + j][y + j] != w[j]) {
+                c = 0;
+            }
+        }
+        return c;
+    }
+    return 0;
+}
+
+void advent2024day04(void) {
+    int p1 = 0, p2 = 0;
+    size_t sz = GRID_SZ;
+    gd = get_lines("input/2024/04", &sz);
+
+    for (size_t x = 0; x < sz; ++x) {
+        for (size_t y = 0; y < sz; ++y) {
+            p1 += horz(x, y, "XMAS");
+            p1 += horz(x, y, "SAMX");
+            p1 += vert(x, y, "XMAS");
+            p1 += vert(x, y, "SAMX");
+            p1 += diag_left(x, y, "XMAS");
+            p1 += diag_left(x, y, "SAMX");
+            p1 += diag_right(x, y, "XMAS");
+            p1 += diag_right(x, y, "SAMX");
+        }
+    }
+
+    printf("%d\n", p1);
+
+    for (size_t x = 1; x < sz - 1; ++x) {
+        for (size_t y = 1; y < sz - 1; ++y) {
+            if (gd[x][y] == 'A') {
+                int c = 0;
+                if ((gd[x - 1][y - 1] == 'M' && gd[x + 1][y + 1] == 'S') || (gd[x - 1][y - 1] == 'S' && gd[x + 1][y + 1] == 'M')) {
+                    if ((gd[x + 1][y - 1] == 'M' && gd[x - 1][y + 1] == 'S') || (gd[x + 1][y - 1] == 'S' && gd[x - 1][y + 1] == 'M')) {
+                        c = 1;
+                    }
+                }
+                p2 += c;
+            }
+        }
+    }
+
+    printf("%d\n", p2);
+
+    del_lines(gd);
+}

src/2024/05.c

@@ -0,0 +1,94 @@
+#include <limits.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "lfinput.h"
+
+#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/2024/06.c

@@ -0,0 +1,110 @@
+#include <advent_utility.h>
+#include <lfutility.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "lfinput.h"
+
+#define TRAVELED 'X'
+#define BLOCK '#'
+
+static int sim(Point guard, char **map, const size_t width, const size_t height) {
+    enum Direction dir = DIR_NORTH;
+    while (guard.x > 0 && guard.y > 0 && guard.x < width && guard.y < height) {
+        map[guard.y][guard.x] = TRAVELED;
+
+        switch (dir) {
+            case DIR_NORTH:
+                if (guard.y == 0) {
+                    break;
+                }
+                if (map[guard.y - 1][guard.x] == BLOCK) {
+                    turn_right(&dir);
+                }
+                break;
+            case DIR_EAST:
+                if (guard.x + 1 == width) {
+                    break;
+                }
+                if (map[guard.y][guard.x + 1] == BLOCK) {
+                    turn_right(&dir);
+                }
+                break;
+            case DIR_SOUTH:
+                if (guard.y + 1 == height) {
+                    break;
+                }
+                if (map[guard.y + 1][guard.x] == BLOCK) {
+                    turn_right(&dir);
+                }
+                break;
+            case DIR_WEST:
+                if (guard.x == 0) {
+                    break;
+                }
+                if (map[guard.y][guard.x - 1] == BLOCK) {
+                    turn_right(&dir);
+                }
+                break;
+        }
+
+        switch (dir) {
+            case DIR_NORTH: guard.y--;
+                break;
+            case DIR_EAST: guard.x++;
+                break;
+            case DIR_SOUTH: guard.y++;
+                break;
+            case DIR_WEST: guard.x--;
+                break;
+        }
+
+        /*
+        for (int y = 0; y < height; y++) {
+            for (int x = 0; x < width; x++) {
+                printf("%c", map[y][x]);
+            }
+            printf("\n");
+        }
+        printf("\n");
+        */
+    }
+
+
+    int v = 0;
+    for (int y = 0; y < height; y++) {
+        for (int x = 0; x < width; x++) {
+            //printf("%c", map[y][x]);
+            if (map[y][x] == TRAVELED) {
+                ++v;
+            }
+        }
+        //printf("\n");
+    }
+
+    return v;
+}
+
+void advent2024day06(void) {
+    size_t height = 0;
+    char **map = get_lines("input/2024/06", &height);
+    const size_t width = strlen(map[0]);
+    Point guard = {.x = 0, .y = 0};
+
+    for (int y = 0; y < height; y++) {
+        for (int x = 0; x < width; x++) {
+            if (map[y][x] == '^') {
+                guard.x = x;
+                guard.y = y;
+                goto GUARD_SEARCH_COMPLETE;
+            }
+        }
+    }
+GUARD_SEARCH_COMPLETE:
+
+    printf("%d\n", sim(guard, map, width, height));
+
+    del_lines(map);
+}

src/2024/07.c

@@ -0,0 +1,13 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "lfinput.h"
+
+void advent2024day07(void) {
+  size_t sz = 0;
+  char **input = get_lines("input/2024/07", &sz);
+
+
+
+  del_lines(input);
+}

src/2024/08.c

@@ -0,0 +1,10 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "lfinput.h"
+
+void advent2024day08(void) {
+  char *input = get_input("input/2024/08");
+  printf("Solution for Day 08 of 2024 is not completed yet\n");
+  free(input);
+}

src/2024/09.c

@@ -0,0 +1,10 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "lfinput.h"
+
+void advent2024day09(void) {
+  char *input = get_input("input/2024/09");
+  printf("Solution for Day 09 of 2024 is not completed yet\n");
+  free(input);
+}

src/2024/10.c

@@ -0,0 +1,10 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "lfinput.h"
+
+void advent2024day10(void) {
+  char *input = get_input("input/2024/10");
+  printf("Solution for Day 10 of 2024 is not completed yet\n");
+  free(input);
+}

src/2024/11.c

@@ -0,0 +1,10 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "lfinput.h"
+
+void advent2024day11(void) {
+  char *input = get_input("input/2024/11");
+  printf("Solution for Day 11 of 2024 is not completed yet\n");
+  free(input);
+}

src/2024/12.c

@@ -0,0 +1,10 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "lfinput.h"
+
+void advent2024day12(void) {
+  char *input = get_input("input/2024/12");
+  printf("Solution for Day 12 of 2024 is not completed yet\n");
+  free(input);
+}

src/2024/13.c

@@ -0,0 +1,10 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "lfinput.h"
+
+void advent2024day13(void) {
+  char *input = get_input("input/2024/13");
+  printf("Solution for Day 13 of 2024 is not completed yet\n");
+  free(input);
+}

src/2024/14.c

@@ -0,0 +1,10 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "lfinput.h"
+
+void advent2024day14(void) {
+  char *input = get_input("input/2024/14");
+  printf("Solution for Day 14 of 2024 is not completed yet\n");
+  free(input);
+}

src/2024/15.c

@@ -0,0 +1,10 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "lfinput.h"
+
+void advent2024day15(void) {
+  char *input = get_input("input/2024/15");
+  printf("Solution for Day 15 of 2024 is not completed yet\n");
+  free(input);
+}

src/2024/16.c

@@ -0,0 +1,10 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "lfinput.h"
+
+void advent2024day16(void) {
+  char *input = get_input("input/2024/16");
+  printf("Solution for Day 16 of 2024 is not completed yet\n");
+  free(input);
+}

src/2024/17.c

@@ -0,0 +1,10 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "lfinput.h"
+
+void advent2024day17(void) {
+  char *input = get_input("input/2024/17");
+  printf("Solution for Day 17 of 2024 is not completed yet\n");
+  free(input);
+}

src/2024/18.c

@@ -0,0 +1,10 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "lfinput.h"
+
+void advent2024day18(void) {
+  char *input = get_input("input/2024/18");
+  printf("Solution for Day 18 of 2024 is not completed yet\n");
+  free(input);
+}

src/2024/19.c

@@ -0,0 +1,10 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "lfinput.h"
+
+void advent2024day19(void) {
+  char *input = get_input("input/2024/19");
+  printf("Solution for Day 19 of 2024 is not completed yet\n");
+  free(input);
+}

src/2024/20.c

@@ -0,0 +1,10 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "lfinput.h"
+
+void advent2024day20(void) {
+  char *input = get_input("input/2024/20");
+  printf("Solution for Day 20 of 2024 is not completed yet\n");
+  free(input);
+}

src/2024/21.c

@@ -0,0 +1,10 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "lfinput.h"
+
+void advent2024day21(void) {
+  char *input = get_input("input/2024/21");
+  printf("Solution for Day 21 of 2024 is not completed yet\n");
+  free(input);
+}

src/2024/22.c

@@ -0,0 +1,10 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "lfinput.h"
+
+void advent2024day22(void) {
+  char *input = get_input("input/2024/22");
+  printf("Solution for Day 22 of 2024 is not completed yet\n");
+  free(input);
+}

src/2024/23.c

@@ -0,0 +1,10 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "lfinput.h"
+
+void advent2024day23(void) {
+  char *input = get_input("input/2024/23");
+  printf("Solution for Day 23 of 2024 is not completed yet\n");
+  free(input);
+}

src/2024/24.c

@@ -0,0 +1,10 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "lfinput.h"
+
+void advent2024day24(void) {
+  char *input = get_input("input/2024/24");
+  printf("Solution for Day 24 of 2024 is not completed yet\n");
+  free(input);
+}

src/2024/25.c

@@ -0,0 +1,10 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "lfinput.h"
+
+void advent2024day25(void) {
+  char *input = get_input("input/2024/25");
+  printf("Solution for Day 25 of 2024 is not completed yet\n");
+  free(input);
+}

src/advent_utility.c

@@ -2,10 +2,11 @@
 #include <string.h>
 #include <stdio.h>
 
+#define PCRE2_CODE_UNIT_WIDTH 8
+#include "pcre2.h"
+
 #if defined __linux__ || defined __APPLE__
-
 #include <openssl/md5.h>
-
 #else
 #include <md5.h>
 #endif
@@ -34,9 +35,9 @@ char *md5_str(const char *input) {
     return md5string;
 }
 
-Vector *string_to_int_vector(const char *input_string, const char* delim) {
+Vector *string_to_int_vector(const char *input_string, const char *delim) {
     char *copy = strdup(input_string);
-    char* token = strtok(copy, delim);
+    char *token = strtok(copy, delim);
     Vector *v = malloc(sizeof(Vector));
     vec_init(v, free);
 
@@ -51,3 +52,127 @@ Vector *string_to_int_vector(const char *input_string, const char* delim) {
     return v;
 }
 
+int int_comp(const void *a, const void *b) {
+    return *(int *) a - *(int *) b;
+}
+
+char **get_matches(char *in, char *pat, size_t *sz, size_t max_matches) {
+    pcre2_code *re;
+    PCRE2_SPTR pattern = (PCRE2_SPTR)pat;
+    int errnum;
+    size_t erroff;
+    PCRE2_SPTR8 substr;
+    size_t substr_sz;
+    PCRE2_SPTR subject = (PCRE2_SPTR)in;
+    size_t subject_sz = strlen(in);
+
+    re = pcre2_compile(pattern, PCRE2_ZERO_TERMINATED, 0, &errnum, &erroff, NULL);
+    if (re == NULL) {
+        char buffer[256];
+        pcre2_get_error_message(errnum, buffer, sizeof(buffer));
+        printf("PCRE2 compilation failed at offset %d: %s\n", (int) erroff, buffer);
+        return NULL;
+    }
+
+    char **matches = NULL;
+    matches = malloc(sizeof(char *) * max_matches);
+    if (matches == NULL) {
+        printf("failed to malloc matches\n");
+        pcre2_code_free(re);
+        return NULL;
+    }
+
+    pcre2_match_data *match_data = pcre2_match_data_create_from_pattern_8(re, NULL);
+    int rc = pcre2_match(re, subject, subject_sz, 0, 0, match_data, NULL);
+    if (rc < 0) {
+        switch (rc) {
+            case PCRE2_ERROR_NOMATCH:
+                printf("PCRE2 no matches\n");
+            break;
+            default:
+                printf("PCRE2 matching error %d\n", rc);
+            break;
+        }
+        pcre2_match_data_free(match_data);
+        pcre2_code_free(re);
+        return NULL;
+    }
+
+    PCRE2_SIZE *ovector = pcre2_get_ovector_pointer(match_data);
+    *sz = 0;
+    for (int i = 0; i < rc; ++i) {
+        substr = subject + ovector[2*i];
+        substr_sz = ovector[2*i+1] - ovector[2*i];
+        matches[*sz] = (char *) malloc(substr_sz + 1);
+        strncpy(matches[*sz], substr, substr_sz);
+        *sz += 1;
+    }
+
+    // Now loop through rest of the matches, if there are any
+    for (;;) {
+        uint32_t options = 0;
+        PCRE2_SIZE start_offset = ovector[1];
+
+        // Check for empty match
+        if (ovector[0] == ovector[1]) {
+            if (ovector[0] == subject_sz) {
+                break;
+            }
+            options = PCRE2_NOTEMPTY_ATSTART | PCRE2_ANCHORED;
+        }
+
+        rc = pcre2_match(re, subject, subject_sz, start_offset, options, match_data, NULL);
+        if (rc == PCRE2_ERROR_NOMATCH) {
+            // All matches have been found
+            if (options == 0) {
+                break;
+            }
+
+            // Handle newlines
+            ovector[1] = start_offset + 1;
+            if (start_offset < subject_sz - 1 &&
+                //subject[start_offset] == '\r' &&
+                subject[start_offset + 1] == '\n') {
+                ovector[1] += 1;
+            }
+            continue;
+        }
+
+        // Other failures, non-recoverable
+        if (rc < 0) {
+            printf("PCRE2 match-matching error %d\n", rc);
+            pcre2_match_data_free(match_data);
+            pcre2_code_free(re);
+            free_matches(matches, *sz);
+            return NULL;
+        }
+
+
+        for (int i = 0; i < rc; ++i) {
+            substr = subject + ovector[2*i];
+            substr_sz = ovector[2*i+1] - ovector[2*i];
+            matches[*sz] = (char *) malloc(substr_sz + 1);
+            strncpy(matches[*sz], substr, substr_sz);
+            *sz += 1;
+        }
+    }
+
+    pcre2_match_data_free(match_data);
+    pcre2_code_free(re);
+    return matches;
+}
+
+void free_matches(char **matches, size_t sz) {
+    for (size_t i = 0; i < sz; ++i) {
+        free(matches[i]);
+    }
+    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;
+}

src/main.c

@@ -16,6 +16,7 @@
 #include "advent2021.h"
 #include "advent2022.h"
 #include "advent2023.h"
+#include "advent2024.h"
 
 int main(int argc, char **argv) {
     if (argc != 3) {
@@ -27,7 +28,7 @@ int main(int argc, char **argv) {
     char buf[32];
     const char *errstr = NULL;
 
-    year = strtonum(argv[1], 15, 23, &errstr);
+    year = strtonum(argv[1], 15, 24, &errstr);
     if (NULL != errstr) {
         printf("Input error: %s\n\n", errstr);
         return 1;
@@ -67,6 +68,9 @@ int main(int argc, char **argv) {
     case 23:
         solutions2023[day - 1]();
         break;
+    case 24:
+        solutions2024[day - 1]();
+        break;
     }
 
     return 0;