day19 done, the ugliest code ever written

2 files changed, 24 insertions, 6 deletions

diff --git a/src/2015/day19/aoc.cpp b/src/2015/day19/aoc.cpp
index 019a120..68f5f52 100644
--- a/src/2015/day19/aoc.cpp
+++ b/src/2015/day19/aoc.cpp
@@ -16,16 +16,20 @@ std::pair<int, int> day19(line_view file) {
   int steps = 0;
 
   line_view lv = m.original;
+  std::vector<molecule::pattern> ps;
 
   do {
     lv = m.replace(lv, &steps);
-    printf("%d\n", steps);
+    // printf("%d\n", steps);
 
-    std::vector<molecule::pattern> ps;
+    ps.clear();
     const char* x = nullptr;
     m.parse_pattern(lv, 0, ps, &x);
-    std::for_each(ps.begin(), ps.end(),
-                  [](molecule::pattern p) { std::cout << p.depth << " -> " << p.lv << std::endl; });
+    // std::for_each(ps.begin(), ps.end(),
+    //              [](molecule::pattern p) { std::cout << p.depth << " -> " << p.lv << std::endl; });
+    if (ps[0].lv == "e") {
+      break;
+    }
     if (ps[0].lv.contains("Y")) {
       std::vector<line_view> ys;
       m.parse_y(ps[0].lv, ys);
@@ -38,11 +42,15 @@ std::pair<int, int> day19(line_view file) {
       }
     } else {
       line_view to = m.deduce(ps[0].lv, &steps);
-      lv = m.replace(lv, {ps[0].lv, to}, ps[0].lv.line);
+      if (!(to == ps[0].lv)) {
+        lv = m.replace(lv, {ps[0].lv, to}, ps[0].lv.line);
+      } else {
+        lv = m.deduce(lv, ps[0].lv.line - 2, &steps);
+      }
     }
   } while (true);
 
-  return {m.distinct(changes), 0};
+  return {m.distinct(changes), steps};
 }
 
 } // namespace aoc2015
diff --git a/src/2015/day19/aoc.h b/src/2015/day19/aoc.h
index af2c720..deb184b 100644
--- a/src/2015/day19/aoc.h
+++ b/src/2015/day19/aoc.h
@@ -81,6 +81,16 @@ struct molecule {
     return lv;
   }
 
+  line_view deduce(line_view lv, const char* p, int* step) {
+    const char* p1 = p;
+    do {
+      p--;
+    } while (backwards.find({p, p1}) == backwards.end());
+    auto it = backwards.find({p, p1});
+    *step += 1;
+    return replace(lv, {it->first, it->second}, p);
+  }
+
   void parse_y(line_view lv, std::vector<line_view>& ys) {
     const char* p1 = lv.line;
     const char* p2 = lv.line + lv.length;