fiddle

2024/19.cpp

@@ -6,8 +6,8 @@
 
 #include <cstdint>
 #include <iostream>
-#include <string_view>
 #include <string>
+#include <string_view>
 #include <tuple>
 #include <vector>
 
@@ -16,44 +16,53 @@ namespace qi = boost::spirit::qi;
 using std::istream;
 using std::ostream;
 using std::size_t;
-using std::string_view;
 using std::string;
+using std::string_view;
 using std::tuple;
 using std::uint64_t;
 using std::vector;
 
-namespace {
-
-auto ways(vector<string> const& towels, string const& design) -> uint64_t
+namespace
 {
-  vector<uint64_t> counts(design.size() + 1);
-  counts[0] = 1;
 
-  for (size_t i = 0; i < design.size(); i++) {
-    auto const suffix = string_view{ begin(design) + i, end(design) };
-    for (auto && towel : towels) {
-      if (suffix.starts_with(towel)) {
-        counts[i + towel.size()] += counts[i];
+  auto ways(const vector<string> &towels, const string &design) -> uint64_t
+  {
+    const auto n = design.size();
+    vector<uint64_t> counts(n + 1);
+    counts[0] = 1;
+
+    for (size_t i = 0; i < n; i++)
+    {
+      string_view const suffix{begin(design) + i, end(design)};
+      for (auto &&towel : towels)
+      {
+        if (suffix.starts_with(towel))
+        {
+          counts[i + towel.size()] += counts[i];
+        }
       }
     }
-  }
 
-  return counts.back();
-}
+    return counts.back();
+  }
 
 } // namespace
 
-auto Main(istream & in, ostream & out) -> void
+auto Main(istream &in, ostream &out) -> void
 {
-  auto const [towels, designs] = 
+  const auto [towels, designs] =
     aocpp::ParseSimple
       <tuple<vector<string>, vector<string>>>
       (in, +qi::alpha % ", " >> "\n\n" >> *(+qi::alpha >> "\n"));
 
   uint64_t p1 = 0, p2 = 0;
-  for (auto && d : designs) {
-    auto const n = ways(towels, d);
-    if (n > 0) { p1++; }
+  for (auto &&design : designs)
+  {
+    const auto n = ways(towels, design);
+    if (n > 0)
+    {
+      p1++;
+    }
     p2 += n;
   }