init, 2015 & 2016

2025-11-14 07:14:53 -08:00
commit ef109439e6
124 changed files with 14861 additions and 0 deletions
--- a/2015/src/01.c
+++ b/2015/src/01.c
@@ -0,0 +1,28 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "lfinput.h"
+
+void advent2015day01(void) {
+    char *input = get_input("input/01");
+    char *c = input;
+    int f = 0, b = 0, s = 1;
+
+    while (*c != '\0') {
+        if (*c == '(') {
+            ++f;
+        } else {
+            --f;
+        }
+
+        if (f == -1 && b == 0) {
+            b = s;
+        }
+
+        ++c;
+        ++s;
+    }
+
+    printf("%d\n%d\n", f, b);
+    free(input);
+}
--- a/2015/src/02.c
+++ b/2015/src/02.c
@@ -0,0 +1,27 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "lfinput.h"
+#include "lfmath.h"
+
+void advent2015day02(void) {
+    size_t sz = 0;
+    char **lines = get_lines("input/02", &sz);
+    int paper = 0, ribbon = 0;
+
+    for (size_t i = 0; i < sz; i++) {
+        char *t = strtok(lines[i], "x");
+        int w = atoi(t);
+        t = strtok(NULL, "x");
+        int l = atoi(t);
+        t = strtok(NULL, "x");
+        int h = atoi(t);
+
+        paper += 2 * l * w + 2 * w * h + 2 * h * l + min_int(w * l, min_int(l * h, h * w));
+        ribbon += l * w * h + min_int(w + w + h + h, min_int(h + h + l + l, l + l + w + w));
+    }
+
+    printf("%d\n%d\n", paper, ribbon);
+    del_lines(lines);
+}
--- a/2015/src/03.c
+++ b/2015/src/03.c
@@ -0,0 +1,89 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "lfset.h"
+#include "lfinput.h"
+#include "lfutility.h"
+
+static int part_two(char *input) {
+    int sx = 0, sy = 0, rx = 0, ry = 0, is_santa = 1;
+    int *x, *y;
+    char *c = input;
+
+    Set *houses = malloc(sizeof(Set));
+    set_init(houses, Point_cmp_v, free);
+
+    while (*c != '\0') {
+        if (is_santa) {
+            x = &sx;
+            y = &sy;
+        } else {
+            x = &rx;
+            y = &ry;
+        }
+        is_santa = is_santa == 1 ? 0 : 1;
+
+        switch (*c) {
+        case '^':
+            ++(*y);
+            break;
+        case 'v':
+            --(*y);
+            break;
+        case '>':
+            ++(*x);
+            break;
+        case '<':
+            --(*x);
+            break;
+        }
+        set_insert(houses, Point_new_p(*x, *y));
+        ++c;
+    }
+
+    int sz = houses->size;
+    set_destroy(houses);
+
+    return sz;
+}
+
+static int part_one(char *input) {
+    int x = 0, y = 0;
+    char *c = input;
+
+    Set *houses = malloc(sizeof(Set));
+    set_init(houses, Point_cmp_v, free);
+
+    while (*c != '\0') {
+        switch (*c) {
+        case '^':
+            ++y;
+            break;
+        case 'v':
+            --y;
+            break;
+        case '>':
+            ++x;
+            break;
+        case '<':
+            --x;
+            break;
+        }
+        set_insert(houses, Point_new_p(x, y));
+        ++c;
+    }
+
+    int sz = houses->size;
+    set_destroy(houses);
+
+    return sz;
+}
+
+void advent2015day03(void) {
+    char *input = get_input("input/03");
+
+    printf("%d\n", part_one(input));
+    printf("%d\n", part_two(input));
+
+    free(input);
+}
--- a/2015/src/04.c
+++ b/2015/src/04.c
@@ -0,0 +1,52 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "lfinput.h"
+#include "advent_utility.h"
+
+static int is_five(char *test) {
+    char *t = test;
+    for (int i = 0; i < 5; ++i, ++t) {
+        if (*t != '0') {
+            return 0;
+        }
+    }
+    return 1;
+}
+
+static int is_six(char *test) {
+    char *t = test;
+    for (int i = 0; i < 6; ++i, ++t) {
+        if (*t != '0') {
+            return 0;
+        }
+    }
+    return 1;
+}
+
+void advent2015day04(void) {
+    char *input = get_input("input/04");
+    int c = 0, five = 0, six = 0;
+
+    while (!five || !six) {
+        int sz = strlen(input) + 8;
+        char test[sz];
+        snprintf(test, sz, "%s%d", input, c);
+        char *md5 = md5_str(test);
+
+        if (!five && is_five(md5)) {
+            five = c;
+            printf("%d\n", five);
+        }
+        if (is_six(md5)) {
+            six = c;
+        }
+
+        free(md5);
+        ++c;
+    }
+
+    printf("%d\n", six);
+    free(input);
+}
--- a/2015/src/05.c
+++ b/2015/src/05.c
@@ -0,0 +1,16 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#include <lfinput.h>
+
+void advent2015day05(void) {
+    /* Sometimes, grep really is the best tool */
+    const char *p1 = capture_system(
+            "grep -E \"(.*[aeiou]){3}\" ./input/2015/05 | grep \"\\(.\\)\\1\" | egrep -v \"(ab|cd|pq|xy)\" | wc -l", 0);
+    const char *p2 = capture_system("grep \"\\(..\\).*\\1\" ./input/2015/05 | grep \"\\(.\\).\\1\" | wc -l", 0);
+
+    printf("%s%s", p1, p2);
+
+    free(p1);
+    free(p2);
+}
--- a/2015/src/06.c
+++ b/2015/src/06.c
@@ -0,0 +1,118 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#ifdef __linux__
+#include <bsd/stdlib.h>
+#endif
+
+#include "lfinput.h"
+#include "lfmath.h"
+
+#define GRID_SZ 1000
+
+typedef struct {
+    int mode; /* 0 = on, 1 = off, 2 = toggle */
+    int x0;
+    int y0;
+    int x1;
+    int y1;
+} s1503;
+
+static void get_coords(char *s, int *x, int *y) {
+    char buf[8];
+    char *c = s;
+    int i = 0;
+    const char *errstr = NULL;
+
+    while (*c != ',') {
+        buf[i++] = *c;
+        ++c;
+    }
+    buf[i] = '\0';
+    *x = (int)strtonum(buf, 0, 999, &errstr);
+    if (NULL != errstr) {
+        exit(1);
+    }
+
+    memset(buf, 0, sizeof(char) * 8);
+    i = 0;
+    ++c;
+    while (*c != '\0') {
+        buf[i++] = *c;
+        ++c;
+    }
+    buf[i] = '\0';
+    *y = (int)strtonum(buf, 0, 999, &errstr);
+    if (NULL != errstr) {
+        exit(1);
+    }
+}
+
+static int run(s1503 *ins, size_t sz, int p1) {
+    int grid[GRID_SZ][GRID_SZ];
+    memset(grid, 0, sizeof(int) * GRID_SZ * GRID_SZ);
+
+    for (size_t i = 0; i < sz; ++i) {
+        for (int x = ins[i].x0; x <= ins[i].x1; ++x) {
+            for (int y = ins[i].y0; y <= ins[i].y1; ++y) {
+                switch (ins[i].mode) {
+                case 0: /* on */
+                    if (p1) { grid[x][y] = 1; }
+                    else {grid[x][y] += 1; }
+                    break;
+
+                case 1: /* off */
+                    if (p1) { grid[x][y] = 0; }
+                    else {grid[x][y] = max_int(0, grid[x][y] - 1); }
+                    break;
+
+                case 2: /* toggle */
+                    if (p1) { grid[x][y] = grid[x][y] == 1 ? 0 : 1; }
+                    else {grid[x][y] += 2; }
+                    break;
+                }
+            }
+        }
+    }
+
+    int c = 0;
+    for (int x = 0; x < GRID_SZ; ++x) {
+        for (int y = 0; y < GRID_SZ; ++y) {
+            c += grid[x][y];
+        }
+    }
+    return c;
+}
+
+void advent2015day06(void) {
+    size_t sz = 0;
+    char **input = get_lines("input/06", &sz);
+    s1503 ins[sz];
+    for (size_t i = 0; i < sz; ++i) {
+        char *s = malloc(sizeof(char) * 64);
+        strncpy(s, input[i], 64);
+        size_t sp_sz = 0;
+        char **sp = split(s, &sp_sz, " ");
+
+        if (sp_sz == 4) {
+            ins[i].mode = 2;
+            get_coords(sp[1], &ins[i].x0, &ins[i].y0);
+            get_coords(sp[3], &ins[i].x1, &ins[i].y1);
+        } else {
+            if (strcmp(sp[1], "on") == 0) {
+                ins[i].mode = 0;
+            } else {
+                ins[i].mode = 1;
+            }
+            get_coords(sp[2], &ins[i].x0, &ins[i].y0);
+            get_coords(sp[4], &ins[i].x1, &ins[i].y1);
+        }
+
+        del_split(sp);
+    }
+    del_lines(input);
+
+    printf("%d\n", run(ins, sz, 1));
+    printf("%d\n", run(ins, sz, 0));
+}
--- a/2015/src/07.c
+++ b/2015/src/07.c
@@ -0,0 +1,118 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stddef.h>
+
+#include "uthash.h"
+#include "lfinput.h"
+#include "lfbool.h"
+
+#ifdef __linux__
+#include <bsd/stdlib.h>
+#else
+#include <stdlib.h>
+#endif
+
+struct Wire {
+    char name[8];
+    uint16_t val;
+    UT_hash_handle hh;
+};
+
+struct Wire *wires = NULL;
+
+static void set_wire(const char *name, int v) {
+    struct Wire *w;
+    HASH_FIND_STR(wires, name, w);
+    if (w == NULL) {
+        w = malloc(sizeof(struct Wire));
+        strlcpy(w->name, name, 8);
+        HASH_ADD_STR(wires, name, w);
+    }
+    w->val = v;
+}
+
+static struct Wire *get_wire(const char *name) {
+    struct Wire *w = NULL;
+    HASH_FIND_STR(wires, name, w);
+    return w;
+}
+
+static void clear_wires() {
+    struct Wire *c, *t;
+    HASH_ITER(hh, wires, c, t) {
+        HASH_DEL(wires, c);
+        free(c);
+    }
+}
+
+static uint16_t get_val(const char* n) {
+    const char *errstr;
+
+    uint16_t v = strtonum(n, 0, 1 << 16, &errstr);
+    if (errstr == NULL) {
+        return v;
+    };
+
+    struct Wire *w = get_wire(n);
+    if (w == NULL) {
+        return 0;
+    }
+    return w->val;
+}
+
+void advent2015day07(void) {
+    size_t sz = 0;
+    char **input = get_lines("input/07", &sz);
+    size_t i = 0;
+    int a_set = LFFALSE;
+
+    while (!a_set) {
+        int sz = strlen(input[i]) + 1;
+        char *buf = malloc(sizeof(char) * sz);
+        strlcpy(buf, input[i], sz);
+        size_t sp_sz = 0;
+        char **sp = split(buf, &sp_sz, " ");
+
+        if (sp_sz == 3) {
+            uint16_t a = get_val(sp[0]);
+            if (a != 0) {
+                set_wire(sp[2], a);
+            }
+        } else if (sp_sz == 4) {
+            uint16_t a = get_val(sp[0]);
+            if (a != 0) {
+                set_wire(sp[2], ~a);
+            }
+        } else {
+            uint16_t a = get_val(sp[0]);
+            uint16_t b = get_val(sp[2]);
+            if (a != 0 && b != 0) {
+                if (strcmp(sp[1], "AND") == 0) {
+                    set_wire(sp[4], a & b);
+                } else if (strcmp(sp[1], "OR") == 0) {
+                    set_wire(sp[4], a | b);
+                } else if (strcmp(sp[1], "LSHIFT") == 0) {
+                    set_wire(sp[4], a << b);
+                } else if (strcmp(sp[1], "RSHIFT") == 0) {
+                    set_wire(sp[4], a >> b);
+                }
+            }
+        }
+
+        uint16_t a = get_val("a");
+        if (a != 0) {
+            a_set = LFTRUE;
+        }
+
+        del_split(sp);
+        ++i;
+        if (i == sz) {
+            i = 0;
+        }
+    }
+
+    printf("%u\n", get_wire("a")->val);
+    del_lines(input);
+    clear_wires();
+}
--- a/2015/src/08.c
+++ b/2015/src/08.c
@@ -0,0 +1,51 @@
+#include <stdio.h>
+#include <string.h>
+
+#include "lfinput.h"
+
+static size_t part_one(char** input, size_t sz) {
+    size_t code = 0, mem = 0;
+
+    for (size_t i = 0; i < sz; ++i) {
+        code += strlen(input[i]);
+        for (size_t j = 1; j < strlen(input[i]) - 1; ++j) {
+            if (input[i][j] == '\\') {
+                if (input[i][j + 1] == '\"' || input[i][j + 1] == '\\') {
+                    ++j;
+                } else {
+                    j += 3;
+                }
+            }
+            ++mem;
+        }
+    }
+
+    return code - mem;
+}
+
+static size_t part_two(char** input, size_t sz) {
+    size_t code = 0, encoded = 0;
+
+    for (size_t i = 0; i < sz; ++i) {
+        code += strlen(input[i]);
+        encoded += 6;
+        for (size_t j = 1; j < strlen(input[i]) - 1; ++j) {
+            if (input[i][j] == '\\' || input[i][j] == '\"') {
+                ++encoded;
+            }
+            ++encoded;
+        }
+    }
+
+    return encoded - code;
+}
+
+void advent2015day08(void) {
+    size_t sz = 0;
+    char **input = get_lines("input/08", &sz);
+
+    printf("%zu\n", part_one(input, sz));
+    printf("%zu\n", part_two(input, sz));
+
+    del_lines(input);
+}
--- a/2015/src/09.c
+++ b/2015/src/09.c
@@ -0,0 +1,10 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "lfinput.h"
+
+void advent2015day09(void) {
+    char *input = get_input("input/09");
+    printf("Solution for Day 09 of 2015 is not completed yet\n");
+    free(input);
+}
--- a/2015/src/10.c
+++ b/2015/src/10.c
@@ -0,0 +1,10 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "lfinput.h"
+
+void advent2015day10(void) {
+    char *input = get_input("input/10");
+    printf("Solution for Day 10 of 2015 is not completed yet\n");
+    free(input);
+}
--- a/2015/src/11.c
+++ b/2015/src/11.c
@@ -0,0 +1,10 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "lfinput.h"
+
+void advent2015day11(void) {
+    char *input = get_input("input/11");
+    printf("Solution for Day 11 of 2015 is not completed yet\n");
+    free(input);
+}
--- a/2015/src/12.c
+++ b/2015/src/12.c
@@ -0,0 +1,10 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "lfinput.h"
+
+void advent2015day12(void) {
+    char *input = get_input("input/12");
+    printf("Solution for Day 12 of 2015 is not completed yet\n");
+    free(input);
+}
--- a/2015/src/13.c
+++ b/2015/src/13.c
@@ -0,0 +1,10 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "lfinput.h"
+
+void advent2015day13(void) {
+    char *input = get_input("input/13");
+    printf("Solution for Day 13 of 2015 is not completed yet\n");
+    free(input);
+}
--- a/2015/src/14.c
+++ b/2015/src/14.c
@@ -0,0 +1,10 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "lfinput.h"
+
+void advent2015day14(void) {
+    char *input = get_input("input/14");
+    printf("Solution for Day 14 of 2015 is not completed yet\n");
+    free(input);
+}
--- a/2015/src/15.c
+++ b/2015/src/15.c
@@ -0,0 +1,63 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "lfinput.h"
+
+typedef struct {
+    long cap;
+    long dur;
+    long flv;
+    long tex;
+    long cal;
+} Ingredient;
+
+static long long_max(long a, long b) {
+    return a > b ? a : b;
+}
+
+void advent2015day15(void) {
+    size_t input_sz = 0;
+    char **input = get_lines("input/15", &input_sz);
+
+    Ingredient ing[input_sz]; for (size_t i = 0; i < input_sz; ++i) {
+        char n[16];
+        sscanf(input[i], "%s capacity %ld, durability %ld, flavor %ld, texture %ld, calories %ld",
+            n, 
+            &ing[i].cap,
+            &ing[i].dur,
+            &ing[i].flv,
+            &ing[i].tex, 
+            &ing[i].cal
+        );
+    }
+
+    long max = 0, max_healthy = 0;
+    for (long p0 = 0; p0 < 100; ++p0) {
+        for (long p1 = 0; p1 < 100; ++p1) {
+            for (long p2 = 0; p2 < 100; ++p2) {
+                for (long p3 = 0; p3 < 100; ++p3) {
+                    if (p0 + p1 + p2 + p3 != 100) {
+                        continue;
+                    }
+                    long cap = long_max(ing[0].cap * p0 + ing[1].cap * p1 + ing[2].cap * p2 + ing[3].cap * p3, 0);
+                    long dur = long_max(ing[0].dur * p0 + ing[1].dur * p1 + ing[2].dur * p2 + ing[3].dur * p3, 0);
+                    long flv = long_max(ing[0].flv * p0 + ing[1].flv * p1 + ing[2].flv * p2 + ing[3].flv * p3, 0);
+                    long tex = long_max(ing[0].tex * p0 + ing[1].tex * p1 + ing[2].tex * p2 + ing[3].tex * p3, 0);
+                    long cal = ing[0].cal * p0 + ing[1].cal * p1 + ing[2].cal * p2 + ing[3].cal * p3;
+                    long score = cap * dur * flv * tex;
+                    if (score > max) {
+                        max = score;
+                    }
+                    if (cal == 500 && score > max_healthy) {
+                        max_healthy = score;
+                    }
+                }
+            }
+        }
+    }
+
+    printf("%ld\n", max);
+    printf("%ld\n", max_healthy);
+
+    del_lines(input);
+}
--- a/2015/src/16.c
+++ b/2015/src/16.c
@@ -0,0 +1,10 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "lfinput.h"
+
+void advent2015day16(void) {
+    char *input = get_input("input/16");
+    printf("Solution for Day 16 of 2015 is not completed yet\n");
+    free(input);
+}
--- a/2015/src/17.c
+++ b/2015/src/17.c
@@ -0,0 +1,10 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "lfinput.h"
+
+void advent2015day17(void) {
+    char *input = get_input("input/17");
+    printf("Solution for Day 17 of 2015 is not completed yet\n");
+    free(input);
+}
--- a/2015/src/18.c
+++ b/2015/src/18.c
@@ -0,0 +1,10 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "lfinput.h"
+
+void advent2015day18(void) {
+    char *input = get_input("input//18");
+    printf("Solution for Day 18 of 2015 is not completed yet\n");
+    free(input);
+}
--- a/2015/src/19.c
+++ b/2015/src/19.c
@@ -0,0 +1,10 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "lfinput.h"
+
+void advent2015day19(void) {
+    char *input = get_input("input/19");
+    printf("Solution for Day 19 of 2015 is not completed yet\n");
+    free(input);
+}
--- a/2015/src/20.c
+++ b/2015/src/20.c
@@ -0,0 +1,10 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "lfinput.h"
+
+void advent2015day20(void) {
+    char *input = get_input("input/20");
+    printf("Solution for Day 20 of 2015 is not completed yet\n");
+    free(input);
+}
--- a/2015/src/21.c
+++ b/2015/src/21.c
@@ -0,0 +1,10 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "lfinput.h"
+
+void advent2015day21(void) {
+    char *input = get_input("input/21");
+    printf("Solution for Day 21 of 2015 is not completed yet\n");
+    free(input);
+}
--- a/2015/src/22.c
+++ b/2015/src/22.c
@@ -0,0 +1,10 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "lfinput.h"
+
+void advent2015day22(void) {
+    char *input = get_input("input/22");
+    printf("Solution for Day 22 of 2015 is not completed yet\n");
+    free(input);
+}
--- a/2015/src/23.c
+++ b/2015/src/23.c
@@ -0,0 +1,10 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "lfinput.h"
+
+void advent2015day23(void) {
+    char *input = get_input("input/23");
+    printf("Solution for Day 23 of 2015 is not completed yet\n");
+    free(input);
+}
--- a/2015/src/24.c
+++ b/2015/src/24.c
@@ -0,0 +1,10 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "lfinput.h"
+
+void advent2015day24(void) {
+    char *input = get_input("input/24");
+    printf("Solution for Day 24 of 2015 is not completed yet\n");
+    free(input);
+}
--- a/2015/src/25.c
+++ b/2015/src/25.c
@@ -0,0 +1,10 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "lfinput.h"
+
+void advent2015day25(void) {
+    char *input = get_input("input/25");
+    printf("Solution for Day 25 of 2015 is not completed yet\n");
+    free(input);
+}
--- a/2015/src/advent_utility.c
+++ b/2015/src/advent_utility.c
@@ -0,0 +1,178 @@
+#include <stdlib.h>
+#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
+
+#include "advent_utility.h"
+
+char *md5_str(const char *input) {
+    unsigned char digest[16];
+
+#if defined __linux__ || defined __APPLE__
+    MD5_CTX context;
+    MD5_Init(&context);
+    MD5_Update(&context, input, strlen(input));
+    MD5_Final(digest, &context);
+#else
+    struct MD5Context context;
+    MD5Init(&context);
+    MD5Update(&context, input, strlen(input));
+    MD5Final(digest, &context);
+#endif
+
+    char *md5string = malloc(33);
+    for (int i = 0; i < 16; ++i) {
+        snprintf(&md5string[i * 2], 33, "%02x", (unsigned int) digest[i]);
+    }
+    return md5string;
+}
+
+Vector *string_to_int_vector(const char *input_string, const char *delim) {
+    char *copy = strdup(input_string);
+    char *token = strtok(copy, delim);
+    Vector *v = malloc(sizeof(Vector));
+    vec_init(v, free);
+
+    while (token != NULL) {
+        int *i = malloc(sizeof(int));
+        *i = atoi(token);
+        vec_push(v, i);
+        token = strtok(NULL, delim);
+    }
+
+    free(copy);
+    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;
+}
--- a/2015/src/main.c
+++ b/2015/src/main.c
@@ -0,0 +1,22 @@
+#include <stdio.h>
+#include <string.h>
+
+#ifdef __linux__
+#include <bsd/stdlib.h>
+#else
+#include <stdlib.h>
+#endif
+
+#include "advent.h"
+
+int main(int argc, char **argv) {
+    int day = 0;
+    printf("Day: ");
+    scanf("%d", &day);
+    if (day < 1 || day > 25) {
+        printf("Invalid day\n");
+        return 1;
+    }
+    solutions2015[day - 1]();
+    return 0;
+}