2 files changed, 61 insertions, 4 deletions

diff --git a/src/2018/day7/aoc.cpp b/src/2018/day7/aoc.cpp
index 6210814..354bfc8 100644
--- a/src/2018/day7/aoc.cpp
+++ b/src/2018/day7/aoc.cpp
@@ -2,8 +2,9 @@
 
 namespace aoc2018 {
 std::map<char, instruction*> instruction::instructions = {};
+size_t instruction::done_total = 0;
 
-void day7(line_view file, char sequence[]) {
+int day7(line_view file, char sequence[]) {
   per_line(file, [](line_view lv) {
     char p1 = *(lv.line + 5);
     char p2 = *(lv.line + 36);
@@ -20,6 +21,36 @@ void day7(line_view file, char sequence[]) {
     n->make_done();
     n = instruction::next();
   }
+
+  auto check = [](int s, instruction** w) {
+    if (*w != nullptr && (*w)->finished(s)) {
+      (*w)->make_done();
+      // std::cout << (*w)->label << " finishes at " << s << std::endl;
+      *w = nullptr;
+    }
+
+    if (*w == nullptr) {
+      instruction::next(w);
+      if (*w != nullptr) {
+        // std::cout << (*w)->label << " starts at " << s << std::endl;
+        (*w)->begin(s);
+      }
+    }
+  };
+
+  instruction::undo();
+  int second{0};
+  instruction* workers[5] = {nullptr, nullptr, nullptr, nullptr, nullptr};
+  // instruction* workers[2] = {nullptr, nullptr};
+  bool stop{false};
+  while (!stop) {
+    for (size_t i = 0; i < ARRAY_SIZE(workers) && !stop; i++) {
+      check(second, &workers[i]);
+    }
+    stop = instruction::all_done();
+    second += int(!stop);
+  }
+  return second;
 }
 
 } // namespace aoc2018
diff --git a/src/2018/day7/aoc.h b/src/2018/day7/aoc.h
index 25d127d..7ea6eb9 100644
--- a/src/2018/day7/aoc.h
+++ b/src/2018/day7/aoc.h
@@ -7,16 +7,26 @@ namespace aoc2018 {
 
 struct instruction {
   static std::map<char, instruction*> instructions;
+  static size_t done_total;
+
+  static bool all_done() { return done_total >= instructions.size(); }
 
   static instruction* make(char x) {
     auto it = instructions.find(x);
     if (it == instructions.end()) {
-      auto p = instructions.insert({x, new instruction{x, false, {}}});
+      auto p = instructions.insert({x, new instruction{x, false, INT32_MAX, {}}});
       return p.first->second;
     }
     return it->second;
   }
 
+  static void undo() {
+    for (auto& kv : instructions) {
+      kv.second->done = false;
+    }
+    done_total = 0;
+  }
+
   static instruction* next() {
     instruction* n = nullptr;
     for (auto& kv : instructions) {
@@ -33,12 +43,27 @@ struct instruction {
     return n; // if nullptr all done
   }
 
+  static void next(instruction** n) {
+    for (auto& kv : instructions) {
+      if (kv.second->ready() && kv.second->start == INT32_MAX) {
+        *n = kv.second;
+        return;
+      }
+    }
+    *n = nullptr;
+  }
+
   char label;
   bool done;
+  int start;
   std::set<instruction*> deps;
 
   void add_dependency(instruction* x) noexcept { deps.insert(x); }
-  void make_done() noexcept { done = true; }
+  void make_done() noexcept {
+    done = true;
+    done_total += 1;
+  }
+  void begin(int s) noexcept { start = s; }
   bool operator<(const instruction& other) const noexcept { return label < other.label; }
 
   bool ready(const std::set<instruction*> ds) const noexcept {
@@ -50,9 +75,10 @@ struct instruction {
     return true;
   }
 
+  bool finished(int s) const noexcept { return start != INT32_MAX && s >= start + label - 'A' + 1 + 60; }
   bool ready() const noexcept { return !done && (deps.empty() || ready(deps)); }
 };
 
-void day7(line_view, char[]);
+int day7(line_view, char[]);
 
 } // namespace aoc2018