From 8f749b3839933c4b70494682a9710e05184465cf Mon Sep 17 00:00:00 2001
From: Mistivia <i@mistivia.com>
Date: Sat, 20 Dec 2025 03:06:21 +0800
Subject: day 3 part 1

---
 03/Makefile | 13 +++++++++++++
 03/part1.c  | 43 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 56 insertions(+)
 create mode 100644 03/Makefile
 create mode 100644 03/part1.c

diff --git a/03/Makefile b/03/Makefile
new file mode 100644
index 0000000..a8f700f
--- /dev/null
+++ b/03/Makefile
@@ -0,0 +1,13 @@
+all: part1 part2
+
+part1: part1.c
+	gcc -g part1.c -o part1 -lalgds
+
+part2: part2.c
+	gcc -g part2.c -o part2 -lalgds
+
+1: part1
+	cat input | ./part1
+
+2: part2
+	cat input | ./part2
\ No newline at end of file
diff --git a/03/part1.c b/03/part1.c
new file mode 100644
index 0000000..be73968
--- /dev/null
+++ b/03/part1.c
@@ -0,0 +1,43 @@
+#include <stdio.h>
+#include <string.h>
+
+#include <algds/str.h>
+#include <algds/vec.h>
+
+
+void getlines(StringVector *lines) {
+    while (1) {
+        char *line = fgetline(stdin);
+        if (line == NULL) {
+            break;
+        }
+        StringVector_push_back(lines, line);
+    }
+}
+
+int find_max(const char *line) {
+    int len = strlen(line);
+    int max = 0;
+    for (int i = 0; i < len - 1; i++) {
+        for (int j = i + 1; j < len; j++) {
+            int n = (line[i] - '0') * 10 + line[j] - '0';
+            if (n > max) {
+                max = n;
+            }
+        }
+    }
+    return max;
+}
+
+int main() {
+    StringVector lines;
+    StringVector_init(&lines);
+    getlines(&lines);
+    String *it = StringVector_begin(&lines);
+    int sum = 0;
+    for (; it != StringVector_end(&lines); it++) {
+        sum += find_max(*it);
+    }
+    printf("%d\n", sum);
+    return 0;
+}
\ No newline at end of file
-- 
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