From e9b7b4becf3ee3fa627f7baa1e813667c712f7c3 Mon Sep 17 00:00:00 2001
From: Evan Burkey <evan@burkey.co>
Date: Thu, 5 Dec 2024 10:33:43 -0800
Subject: [PATCH] 2024-04

---
 src/2024/02.c        | 12 +-----
 src/2024/04.c        | 92 +++++++++++++++++++++++++++++++++++++++++---
 src/advent_utility.c |  1 +
 3 files changed, 89 insertions(+), 16 deletions(-)

diff --git a/src/2024/02.c b/src/2024/02.c
index 98d1e33..9617282 100644
--- a/src/2024/02.c
+++ b/src/2024/02.c
@@ -102,17 +102,7 @@ void advent2024day02(void) {
         }
 
         p1 += part1(a);
-        //p2 += part2(a);
-
-        int s = part2(a);
-        if (s) {
-            LL_ITER(a) {
-                int *str = node->data;
-                printf("%d ", *str);
-            }
-            printf("\n");
-            p2 += s;
-        }
+        p2 += part2(a);
 
         free(sp);
         ll_destroy(a);
diff --git a/src/2024/04.c b/src/2024/04.c
index e93100d..f09c6e0 100644
--- a/src/2024/04.c
+++ b/src/2024/04.c
@@ -1,10 +1,92 @@
 #include <stdio.h>
-#include <stdlib.h>
+#include <string.h>
 
 #include "lfinput.h"
 
-void advent2024day04(void) {
-  char *input = get_input("input/2024/04");
-  printf("Solution for Day 04 of 2024 is not completed yet\n");
-  free(input);
+#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);
 }
diff --git a/src/advent_utility.c b/src/advent_utility.c
index 6414f50..e8a942c 100644
--- a/src/advent_utility.c
+++ b/src/advent_utility.c
@@ -143,6 +143,7 @@ char **get_matches(char *in, char *pat, size_t *sz, size_t max_matches) {
             printf("PCRE2 match-matching error %d\n", rc);
             pcre2_match_data_free(match_data);
             pcre2_code_free(re);
+            free_matches(matches, *sz);
             return NULL;
         }