From 26dd9df8c73101b3df48d6de98a3d1e736df27e7 Mon Sep 17 00:00:00 2001
From: Lucia Ceionia <lucia@ceionia.com>
Date: Wed, 3 Dec 2025 02:08:01 -0600
Subject: [PATCH] day 3

---
 day3.c | 128 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 128 insertions(+)
 create mode 100644 day3.c

diff --git a/day3.c b/day3.c
new file mode 100644
index 0000000..4f79b53
--- /dev/null
+++ b/day3.c
@@ -0,0 +1,128 @@
+#include "lib.h"
+
+#define DBG 0
+
+static
+unsigned char input[] = {
+#embed "day3_input.txt"
+};
+
+static
+unsigned char test[] = {
+#embed "day3_test.txt"
+};
+
+
+static
+unsigned long do_part1(size_t file_len, unsigned char file[file_len]) {
+    unsigned long result = 0;
+    unsigned char *s = file;
+
+    do {
+        unsigned char n0 = 0, n1 = 0;
+        unsigned char *n0p = NULL;
+        do {
+            if (s[0] > n0) {
+                n0 = s[0];
+                n0p = s;
+            }
+            s++;
+        } while (s[1] != '\n');
+        s = n0p+1;
+        do {
+            if (s[0] > n1) {
+                n1 = s[0];
+            }
+            s++;
+        } while (s[0] != '\n');
+        s++;
+        unsigned n = (n0 - '0') * 10 + (n1 - '0');
+        result += n;
+    } while(s < &file[file_len]);
+
+    return result;
+}
+
+static
+unsigned long do_part2(size_t file_len, unsigned char file[file_len]) {
+    unsigned long result = 0;
+    unsigned char *s = file;
+
+    do {
+        // for some reason this crashes
+        // but works fine under blink so.
+        // whatever
+        unsigned char n[12] = { };
+        unsigned char *np[12] = { };
+        for (int i = 0; i < 12; i++) {
+            do {
+                if (s[0] > n[i]) {
+                    n[i] = s[0];
+                    np[i] = s;
+                }
+                s++;
+            } while (s[11-i] != '\n');
+            s = np[i]+1;
+        }
+        unsigned long v = 0;
+        for (int i = 0; i < 12; i++) {
+            v = v * 10 + (n[i] - '0');
+        }
+#if DBG
+        print("got ");
+        printd(v);
+        print("\n");
+#endif
+        result += v;
+        while (*s != '\n') s++;
+        s++;
+    } while(s < &file[file_len]);
+
+    return result;
+}
+
+#define RUN_TEST1 1
+#define RUN_PART1 1
+#define RUN_TEST2 1
+#define RUN_PART2 1
+
+#define TEST1_EXPECT 357
+#define TEST2_EXPECT 3121910778619
+
+void _start() {
+#if RUN_TEST1
+    print("PART 1 TEST: ");
+    if (unsigned long v = do_part1(countof(test), test); v != TEST1_EXPECT) {
+        print("FAILED (got ");
+        printd(v);
+        print(", expected " xstr(TEST1_EXPECT) ")\n");
+    } else {
+        print("PASSED\n");
+    }
+#endif
+
+#if RUN_PART1
+    print("PART 1 RESULT: ");
+    printd(do_part1(countof(input), input));
+    print("\n");
+#endif
+
+#if RUN_TEST2
+    print("PART 2 TEST: ");
+    if (unsigned long v = do_part2(countof(test), test); v != TEST2_EXPECT) {
+        print("FAILED (got ");
+        printd(v);
+        print(", expected " xstr(TEST2_EXPECT) ")\n");
+    } else {
+        print("PASSED\n");
+    }
+#endif
+
+#if RUN_PART2
+    print("PART 2 RESULT: ");
+    printd(do_part2(countof(input), input));
+    print("\n");
+#endif
+
+    syscall(SYS_exit_group, 0);
+}