2 files changed, 16 insertions, 6 deletions
diff --git a/src/2015/day2/aoc.cpp b/src/2015/day2/aoc.cpp
index 33ae6b6..a23d9ad 100644
--- a/src/2015/day2/aoc.cpp
+++ b/src/2015/day2/aoc.cpp
@@ -35,23 +35,33 @@ box parse_day2(line_view lv) {
   return b;
 }
 
-inline int min_day2(box b) {
+inline int min_square(box b) {
   int x1 = b.l * b.w;
   int x2 = b.l * b.h;
   int x3 = b.h * b.w;
   return std::min(std::min(x1, x2), x3);
 }
 
+inline int min_perimeter(box b) {
+  int x1 = b.l + b.w;
+  int x2 = b.l + b.h;
+  int x3 = b.h + b.w;
+  return 2 * std::min(std::min(x1, x2), x3);
+}
+
 inline int surface(box b) { return 2 * b.l * b.w + 2 * b.l * b.h + 2 * b.w * b.h; }
+inline int squire(box b) { return b.l * b.w * b.h; }
 
-int day2(line_view input) {
+std::pair<int, int> day2(line_view input) {
   int total = 0;
-  per_line(input, [&total](line_view line) {
+  int ribbon = 0;
+  per_line(input, [&total, &ribbon](line_view line) {
     box b = parse_day2(line);
-    total += surface(b) + min_day2(b);
+    total += surface(b) + min_square(b);
+    ribbon += squire(b) + min_perimeter(b);
     return true;
   });
-  return total;
+  return {total, ribbon};
 }
 
 } // namespace aoc2015
diff --git a/src/2015/day2/aoc.h b/src/2015/day2/aoc.h
index 72402cf..66fe384 100644
--- a/src/2015/day2/aoc.h
+++ b/src/2015/day2/aoc.h
@@ -13,6 +13,6 @@ struct box {
 box parse_day2(line_view lv);
 int min_day2(box);
 int surface(box);
-int day2(line_view);
+std::pair<int, int> day2(line_view);
 
 } // namespace aoc2015