1 files changed, 50 insertions, 1 deletions
diff --git a/src/2017/day11/aoc.cpp b/src/2017/day11/aoc.cpp
index f6b5864..9c6f780 100644
--- a/src/2017/day11/aoc.cpp
+++ b/src/2017/day11/aoc.cpp
@@ -2,5 +2,54 @@
 
 namespace aoc2017 {
 
-std::pair<int64_t, int64_t> day11(line_view) { return {0, 0}; }
+void route(hd in, hd out, int* step) {
+  constexpr static int steps[6][6] = {
+    {1, 1, 1, 0, 0, -1},
+    {1, 1, 0, 1, -1, 0}, // ne
+    {1, 0, 1, -1, 1, 0}, // nw
+    {0, 1, -1, 1, 0, 1}, // se
+    {0, -1, 1, 0, 1, 1}, // sw
+    {-1, 0, 0, 1, 1, 1},
+  };
+
+  auto x = static_cast<int>(in);
+  auto y = static_cast<int>(out);
+  *step += steps[x][y];
+}
+
+hd inout(hd x) {
+  hd d6[] = {hd::s, hd::sw, hd::se, hd::nw, hd::ne, hd::n};
+  return d6[static_cast<int>(x)];
+}
+
+std::pair<int64_t, int64_t> day11(line_view file) {
+  std::vector<hd> ds;
+  const char* p0 = file.line;
+  const char* p1 = p0;
+  line_view d6[] = {"n", "ne", "nw", "se", "sw", "s"};
+  while (p1 < file.line + file.length) {
+    if (*p1 == ',' || *p1 == '\n') {
+      line_view d{p0, p1};
+      for (int i = 0; i < 6; i++) {
+        if (d6[i] == d) {
+          ds.push_back(static_cast<hd>(i));
+          break;
+        }
+      }
+      p0 = p1 + 1;
+    }
+    p1++;
+  }
+
+  int step{1};
+  for (size_t i = 0; i < ds.size() - 1; i++) {
+    auto j = i + 1;
+    hd in = inout(ds[i]);
+    hd out = ds[j];
+    route(in, out, &step);
+  }
+  printf("%d\n", step);
+  return {0, 0};
+}
+
 } // namespace aoc2017