1 files changed, 14 insertions, 15 deletions

diff --git a/2024/19/day19b.cpp b/2024/19/day19b.cpp
index 6f8b8f4..dd6055d 100644
--- a/2024/19/day19b.cpp
+++ b/2024/19/day19b.cpp
@@ -11,28 +11,27 @@
 #include <vector>
 using namespace std;
 
-vector<string> gettowels(const string& line) {
-        vector<string> ret;
-        int j = 0;
-        for (int i = 0; j != -1; i = j+2) {
+vector<string_view> gettowels(const string_view& line) {
+        vector<string_view> ret;
+        unsigned sz = line.size();
+        for (int i = 0, j = 0; j != -1; i = j+2) {
                 j = line.find(",", i);
-                ret.push_back(line.substr(i, (j == -1 ? line.size() : j)-i));
+                ret.push_back(line.substr(i, (j == -1 ? sz : j) - i));
         }
         return ret;
 }
 
-int64_t countpossible(const string& p, const vector<string>& towels, vector<int64_t>& mem) {
-        if (p.size() == 0)
-                return 1;
-        if (mem[p.size()] != -1)
-                return mem[p.size()];
+int64_t f(const string_view& p, const vector<string_view>& towels, vector<int64_t>& mem) {
+        unsigned lp = p.size();
+        if (lp == 0) return 1;
+        if (mem[lp] != -1) return mem[lp];
         int64_t ret = 0;
         for (auto t : towels) {
-                if (t == p.substr(0, t.size()))
-                        ret += countpossible(p.substr(
-                            t.size(), p.size() - t.size()), towels, mem);
+                unsigned lt = t.size();
+                if (t == p.substr(0, lt))
+                        ret += f(p.substr(lt, lp - lt), towels, mem);
         }
-        return (mem[p.size()] = ret);
+        return (mem[lp] = ret);
 }
 
 int main() {
@@ -47,7 +46,7 @@ int main() {
         int64_t count = 0;
         for (auto p : patterns) {
                 for (auto& m : mem) m = -1;
-                count += countpossible(p, towels, mem);
+                count += f(p, towels, mem);
         }
         cout << count << endl;
         return 0;