2024 day 19

2024/19/main-1.cpp

@@ -0,0 +1,41 @@
+#include "../../include/aoc.hpp"
+#include <bits/stdc++.h>
+using namespace std;
+
+vector<string> towels;
+
+bool rec(string_view s) {
+	if (s.empty()) {
+		return true;
+	}
+	for (auto &t : towels) {
+		if (s.starts_with(t) && rec(s.substr(t.size()))) {
+			return true;
+		}
+	}
+	return false;
+}
+
+int main() {
+	ios::sync_with_stdio(0);
+	cin.tie(0);
+
+	string line;
+	getline(cin, line);
+	istringstream ll(line);
+	string s;
+	while (getline(ll, s, ',')) {
+		towels.push_back(s);
+		ll.ignore();
+	}
+
+	cin.ignore();
+	ull count = 0;
+	while (getline(cin, line)) {
+		if (rec(line)) {
+			count++;
+		}
+	}
+
+	cout << count << '\n';
+}

2024/19/main-2.cpp

@@ -0,0 +1,53 @@
+#include "../../include/aoc.hpp"
+#include <bits/stdc++.h>
+using namespace std;
+
+unordered_map<string_view, ull> m;
+vector<string> towels;
+vector<string> designs;
+
+ull rec(string_view s) {
+	if (s.empty()) {
+		return 1;
+	}
+	if (m.contains(s)) {
+		return m[s];
+	}
+	ull c = 0;
+	for (auto &t : towels) {
+		if (s.starts_with(t)) {
+			c += rec(s.substr(t.size()));
+		}
+	}
+	m[s] = c;
+	return c;
+}
+
+int main() {
+	ios::sync_with_stdio(0);
+	cin.tie(0);
+
+	string line;
+	getline(cin, line);
+	istringstream ll(line);
+	string s;
+	while (getline(ll, s, ',')) {
+		towels.push_back(s);
+		ll.ignore();
+	}
+
+	cin.ignore();
+	while (getline(cin, line)) {
+		designs.push_back(line);
+	}
+
+	// NOTE: designs gets their own global vector to make sure that the design
+	// strings live for as long as the memo does (it happened to work on the
+	// full data the first try without it but don't rely on that)
+	ull count = 0;
+	for (string &design : designs) {
+		count += rec(design);
+	}
+
+	cout << count << '\n';
+}