1 files changed, 35 insertions, 0 deletions
diff --git a/src/2015/day12/aoc.cpp b/src/2015/day12/aoc.cpp
index 1c33c66..3b1ed2b 100644
--- a/src/2015/day12/aoc.cpp
+++ b/src/2015/day12/aoc.cpp
@@ -2,4 +2,39 @@
 
 namespace aoc2015 {
 
+int parse_day12(const char* p1, const char* p2) {
+  int sign = *(p1 - 1) == '-' ? -1 : 1;
+  int d{0};
+  while (p1 != p2) {
+    d = d * 10 + *p1 - '0';
+    p1++;
+  }
+  return sign * d;
 }
+
+int day12(line_view file) {
+  int total = 0;
+  const char* p1 = file.line;
+  const char* p2 = p1;
+  bool to_parse = false;
+  while (p2 < file.line + file.length) {
+    if (*p2 >= '0' && *p2 <= '9') {
+      if (!to_parse) {
+        p1 = p2;
+        to_parse = !to_parse;
+      }
+    } else {
+      if (to_parse) {
+        total += parse_day12(p1, p2);
+        to_parse = !to_parse;
+      }
+    }
+    p2++;
+  }
+  if (to_parse) {
+    total += parse_day12(p1, p2);
+  }
+  return total;
+}
+
+} // namespace aoc2015