From 14967ae07e7195a0336a3f2a51347aa779c34946 Mon Sep 17 00:00:00 2001
From: Michael Adler <adlerm@mailbox.org>
Date: Sun, 3 Dec 2023 22:43:41 +0100
Subject: [PATCH] Day 3: Refactor

---
 include/aoc/macros.h |   1 +
 src/day03/solve.c    | 104 ++++++++++---------------------------------
 2 files changed, 24 insertions(+), 81 deletions(-)

diff --git a/include/aoc/macros.h b/include/aoc/macros.h
index 3596ee1..b31c940 100644
--- a/include/aoc/macros.h
+++ b/include/aoc/macros.h
@@ -31,3 +31,4 @@
         (x) = (y);                                                             \
         (y) = temp;                                                            \
     } while (0)
+#define ARRAY_LENGTH(x) (sizeof(x) / sizeof((x)[0]))
diff --git a/src/day03/solve.c b/src/day03/solve.c
index d1b87ce..2bd1d25 100644
--- a/src/day03/solve.c
+++ b/src/day03/solve.c
@@ -5,14 +5,18 @@
 #define MAX_SYMBOLS 4096
 #define EMPTY -1
 
+typedef struct {
+    int x;
+    int y;
+    char value;
+} Symbol;
+
 static inline bool is_symbol(char s) {
-    if (s >= '0' && s <= '9') { return false; }
-    if (s == '.') { return false; }
-    return true;
+    return !(s >= '0' && s <= '9') && s != '.';
 }
 
-static int collect(int8_t numbers[MAX_NUMBERS][MAX_NUMBERS], int cols,
-                   int candidate_x, int candidate_y) {
+static inline int collect(int8_t numbers[MAX_NUMBERS][MAX_NUMBERS], int cols,
+                          int candidate_x, int candidate_y) {
     // go left as far as possible to find start digit
     while (candidate_x - 1 >= 0 &&
            numbers[candidate_y][candidate_x - 1] != EMPTY) {
@@ -30,12 +34,6 @@ static int collect(int8_t numbers[MAX_NUMBERS][MAX_NUMBERS], int cols,
     return value;
 }
 
-typedef struct {
-    int x;
-    int y;
-    char value;
-} Symbol;
-
 void solve(const char *buf, size_t buf_size, Solution *result) {
     int cols = 0;
     while (buf[cols] != '\n') cols++;
@@ -71,82 +69,26 @@ void solve(const char *buf, size_t buf_size, Solution *result) {
         int values[8];
         int value_idx = 0;
 
-        { // top left
-            int candidate_y = y - 1;
-            int candidate_x = x - 1;
-            if (candidate_y >= 0 && candidate_x >= 0 &&
-                numbers[candidate_y][candidate_x] != EMPTY) {
-                values[value_idx++] =
-                    collect(numbers, cols, candidate_x, candidate_y);
-            }
-        }
-        { // top
-            int candidate_y = y - 1;
-            int candidate_x = x;
-            if (candidate_y >= 0 &&
-                numbers[candidate_y][candidate_x] != EMPTY) {
-                values[value_idx++] =
-                    collect(numbers, cols, candidate_x, candidate_y);
-            }
-        }
-        { // top right
-            int candidate_y = y - 1;
-            int candidate_x = x + 1;
-            if (candidate_y >= 0 && candidate_x < cols &&
-                numbers[candidate_y][candidate_x] != EMPTY) {
-                values[value_idx++] =
-                    collect(numbers, cols, candidate_x, candidate_y);
-            }
-        }
-
-        { // left
-            int candidate_y = y;
-            int candidate_x = x - 1;
-            if (candidate_x >= 0 &&
-                numbers[candidate_y][candidate_x] != EMPTY) {
-                values[value_idx++] =
-                    collect(numbers, cols, candidate_x, candidate_y);
-            }
-        }
-        { // right
-            int candidate_y = y;
-            int candidate_x = x + 1;
-            if (candidate_x < cols &&
-                numbers[candidate_y][candidate_x] != EMPTY) {
-                values[value_idx++] =
-                    collect(numbers, cols, candidate_x, candidate_y);
-            }
-        }
+        Point2D deltas[] = {
+            {-1, -1}, // top left
+            {0, -1},  // top
+            {1, -1},  // top right
+            {-1, 0},  // left
+            {1, 0},   // right
+            {-1, 1},  // bottom left
+            {0, 1},   // bottom
+            {1, 1}    // bottom right
+        };
 
-        { // bottom left
-            int candidate_y = y + 1;
-            int candidate_x = x - 1;
-            if (candidate_y < rows && candidate_x >= 0 &&
-                numbers[candidate_y][candidate_x] != EMPTY) {
-                values[value_idx++] =
-                    collect(numbers, cols, candidate_x, candidate_y);
-            }
-        }
-        { // bottom
-            int candidate_y = y + 1;
-            int candidate_x = x;
-            if (candidate_y < rows &&
+        for (size_t i = 0; i < ARRAY_LENGTH(deltas); i++) {
+            int candidate_x = x + deltas[i].x, candidate_y = y + deltas[i].y;
+            if (candidate_x >= 0 && candidate_y >= 0 && candidate_x < cols &&
+                candidate_y < rows &&
                 numbers[candidate_y][candidate_x] != EMPTY) {
                 values[value_idx++] =
                     collect(numbers, cols, candidate_x, candidate_y);
             }
         }
-        { // bottom right
-            int candidate_y = y + 1;
-            int candidate_x = x + 1;
-            if (candidate_y < rows && candidate_x < cols &&
-                numbers[candidate_y][candidate_x] != EMPTY) {
-                values[value_idx++] =
-                    collect(numbers, cols, candidate_x, candidate_y);
-                ;
-            }
-        }
-
         for (int i = 0; i < value_idx; i++) { part1 += values[i]; }
         if (is_star && value_idx == 2) { part2 += values[0] * values[1]; }
     }