1 files changed, 48 insertions, 1 deletions
diff --git a/src/2017/day11/aoc.cpp b/src/2017/day11/aoc.cpp
index b9b599a..c7e5ffd 100644
--- a/src/2017/day11/aoc.cpp
+++ b/src/2017/day11/aoc.cpp
@@ -1,7 +1,52 @@
 #include "aoc.h"
+#include <deque>
+#include <set>
 
 namespace aoc2017 {
 
+hexagon route(hexagon h, const std::vector<hd>& hds, int* max) {
+  for (auto& hd : hds) {
+    h = h.neighbour(hd);
+    int d = h.a + h.r + h.c;
+    if (d > *max) {
+      *max = d;
+    }
+  }
+  return h;
+}
+
+int bfs(hexagon start, hexagon target) {
+  int step{0};
+  std::deque<hexagon> q;
+  std::set<hexagon> visited;
+  q.push_back(start);
+
+  while (!q.empty()) {
+    auto s = q.size();
+    while (s-- > 0) {
+      auto h = q.front();
+      q.pop_front();
+      if (h == target) {
+        return step;
+      }
+
+      hexagon ns[6] = {
+          h.neighbour(hd::n),  h.neighbour(hd::nw), h.neighbour(hd::ne),
+          h.neighbour(hd::sw), h.neighbour(hd::se), h.neighbour(hd::s),
+      };
+      for (auto& n : ns) {
+        if (visited.find(n) == visited.end()) {
+          visited.insert(n);
+          q.push_back(n);
+        }
+      }
+    }
+    step++;
+  }
+
+  return INT32_MAX;
+}
+
 std::pair<int64_t, int64_t> day11(line_view file) {
   std::vector<hd> ds;
   const char* p0 = file.line;
@@ -21,7 +66,9 @@ std::pair<int64_t, int64_t> day11(line_view file) {
     p1++;
   }
 
-  return {0, 0};
+  int max{INT32_MIN};
+  auto d = route({0, 0, 0}, ds, &max);
+  return {d.a + d.r + d.c, max};
 }
 
 } // namespace aoc2017