From 21e1237e93703f632253f042bd5877998d81c507 Mon Sep 17 00:00:00 2001
From: Sebastiano Tronto <sebastiano@tronto.net>
Date: Mon, 23 Dec 2024 07:55:11 +0100
Subject: Day 23 2024

---
 2024/23/Makefile   | 11 +++++++++
 2024/23/day23a.cpp | 40 +++++++++++++++++++++++++++++++++
 2024/23/day23b.cpp | 66 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 2024/learned.txt   |  1 +
 4 files changed, 118 insertions(+)
 create mode 100644 2024/23/Makefile
 create mode 100644 2024/23/day23a.cpp
 create mode 100644 2024/23/day23b.cpp

diff --git a/2024/23/Makefile b/2024/23/Makefile
new file mode 100644
index 0000000..ad85264
--- /dev/null
+++ b/2024/23/Makefile
@@ -0,0 +1,11 @@
+CC=g++ -std=c++20 -g -Wall
+
+a:
+	${CC} -o a.out day23a.cpp
+	./a.out
+
+b:
+	${CC} -o b.out day23b.cpp
+	./b.out
+
+.PHONY: a b
diff --git a/2024/23/day23a.cpp b/2024/23/day23a.cpp
new file mode 100644
index 0000000..048a724
--- /dev/null
+++ b/2024/23/day23a.cpp
@@ -0,0 +1,40 @@
+#include <algorithm>
+#include <cstdint>
+#include <iostream>
+#include <map>
+#include <queue>
+#include <ranges>
+#include <set>
+#include <sstream>
+#include <string>
+#include <string_view>
+#include <vector>
+using namespace std;
+
+set<int> computers;
+bool m[26*26][26*26];
+
+int index(char a, char b) { return (int)(a-'a') + 26*(int)(b-'a'); }
+bool t(int i) { return i % 26 == 't' - 'a'; }
+
+int main() {
+	string line;
+	while (getline(cin, line)) {
+		int i = index(line[0], line[1]);
+		int j = index(line[3], line[4]);
+		computers.insert(i);
+		computers.insert(j);
+		m[i][j] = m[j][i] = true;
+	}
+
+	vector cv(computers.begin(), computers.end());
+	int tot = 0;
+	for (unsigned i = 0; i < cv.size(); i++)
+		for (unsigned j = i+1; j < cv.size(); j++)
+			for (unsigned k = j+1; k < cv.size(); k++)
+				tot += m[cv[i]][cv[j]] && m[cv[j]][cv[k]] && m[cv[k]][cv[i]] &&
+				       (t(cv[i]) || t(cv[j]) || t(cv[k]));
+
+	cout << tot << endl;
+	return 0;
+}
diff --git a/2024/23/day23b.cpp b/2024/23/day23b.cpp
new file mode 100644
index 0000000..6b8d12f
--- /dev/null
+++ b/2024/23/day23b.cpp
@@ -0,0 +1,66 @@
+#include <algorithm>
+#include <cstdint>
+#include <iostream>
+#include <map>
+#include <queue>
+#include <ranges>
+#include <set>
+#include <sstream>
+#include <string>
+#include <string_view>
+#include <vector>
+using namespace std;
+
+set<int> computers;
+bool m[26*26][26*26];
+
+int index(char a, char b) { return (int)(b-'a') + 26*(int)(a-'a'); }
+void printnode(int i) { cout << (char)('a'+i/26) << (char)('a'+i%26); }
+bool t(int i) { return i % 26 == 't' - 'a'; }
+
+bool all(int i, const set<int>& v) {
+	for (auto j : v)
+		if (!m[i][j])
+			return false;
+	return true;
+}
+
+int main() {
+	string line;
+	while (getline(cin, line)) {
+		int i = index(line[0], line[1]);
+		int j = index(line[3], line[4]);
+		computers.insert(i);
+		computers.insert(j);
+		m[i][j] = m[j][i] = true;
+	}
+
+	vector<set<int>> cliques[15];
+	cliques[0].push_back(set<int>());
+	for (int i = 1; ; i++) {
+		for (auto& c : cliques[i-1]) {
+			int mm = *max_element(c.begin(), c.end());
+			for (auto j : computers) {
+				if (j <= mm) continue;
+				if (all(j, c)) {
+					set nw = c;
+					nw.insert(j);
+					cliques[i].push_back(nw);
+				}
+			}
+		}
+		auto n = cliques[i].size();
+		cout << "Found " << n << " cliques of size " << i << endl;
+		if (n == 0) break;
+		auto cc = *cliques[i].begin();
+		vector<int> cv(cc.begin(), cc.end());
+		sort(cv.begin(), cv.end());
+		for (auto j : cv) {
+			printnode(j);
+			cout << ",";
+		}
+		cout << endl;
+	}
+
+	return 0;
+}
diff --git a/2024/learned.txt b/2024/learned.txt
index ba00c6c..8dce20a 100644
--- a/2024/learned.txt
+++ b/2024/learned.txt
@@ -10,3 +10,4 @@ List of things I learned (or refreshed) with this year's AoC.
 * Day 9: std::views
 * Day 11: if(init; cond)
 * Day 19: more practice with std::string_view for constant string
+* Day 22: std::views::values for map (and keys)
-- 
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