1 files changed, 8 insertions, 4 deletions
diff --git a/src/2017/day9/aoc.cpp b/src/2017/day9/aoc.cpp
index 0b1cda6..9047aef 100644
--- a/src/2017/day9/aoc.cpp
+++ b/src/2017/day9/aoc.cpp
@@ -13,7 +13,7 @@ static void take(const char* p, std::stack<char>& gs, int* t) {
   }
 }
 
-static bool is_valid(const char* p, std::stack<char>& g) {
+static bool is_valid(const char* p, std::stack<char>& g, int* t) {
   if (g.empty()) {
     if (*p == '!') {
       g.push(*p);
@@ -25,11 +25,14 @@ static bool is_valid(const char* p, std::stack<char>& g) {
     if (g.top() == '!') {
       g.pop();
     } else {
+      *t += 1;
       if (*p == '>') {
         g.pop();
+        *t -= 1;
       }
       if (*p == '!') {
         g.push(*p);
+        *t -= 1;
       }
     }
   }
@@ -37,18 +40,19 @@ static bool is_valid(const char* p, std::stack<char>& g) {
   return g.empty();
 }
 
-int day9(line_view file) {
+std::pair<int, int> day9(line_view file) {
   int t0{0};
+  int t1{0};
   std::stack<char> gs;
   std::stack<char> gv;
   const char* p = file.line;
   while (p < file.line + file.length) {
-    if (is_valid(p, gv)) {
+    if (is_valid(p, gv, &t1)) {
       take(p, gs, &t0);
     }
     p++;
   }
-  return t0;
+  return {t0, t1};
 }
 
 } // namespace aoc2017