From 3418444a8da97e5a05f87f9737bed94edd43ec60 Mon Sep 17 00:00:00 2001
From: Sebastiano Tronto <sebastiano@tronto.net>
Date: Wed, 11 Dec 2024 07:03:12 +0100
Subject: Day 11 2024

---
 2024/11/Makefile   | 24 +++++++++++++++++++++
 2024/11/day11a.cpp | 57 +++++++++++++++++++++++++++++++++++++++++++++++++
 2024/11/day11b.cpp | 62 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 2024/learned.txt   |  1 +
 4 files changed, 144 insertions(+)
 create mode 100644 2024/11/Makefile
 create mode 100644 2024/11/day11a.cpp
 create mode 100644 2024/11/day11b.cpp

(limited to '2024')

diff --git a/2024/11/Makefile b/2024/11/Makefile
new file mode 100644
index 0000000..a5d27bb
--- /dev/null
+++ b/2024/11/Makefile
@@ -0,0 +1,24 @@
+CC=g++ -std=c++20 -g -Wall
+
+a:
+	${CC} -o a.out day11a.cpp
+
+b:
+	${CC} -o b.out day11b.cpp
+
+clean:
+	rm -f a b
+
+atest: a
+	./a.out
+
+btest: b
+	./b.out
+
+arun: a
+	./a.out < input
+
+brun: b
+	./b.out < input
+
+.PHONY: a b clean atest btest arun brun
diff --git a/2024/11/day11a.cpp b/2024/11/day11a.cpp
new file mode 100644
index 0000000..50c3ebf
--- /dev/null
+++ b/2024/11/day11a.cpp
@@ -0,0 +1,57 @@
+#include <algorithm>
+#include <cstdint>
+#include <iostream>
+#include <map>
+#include <ranges>
+#include <set>
+#include <sstream>
+#include <string>
+#include <string_view>
+#include <vector>
+using namespace std;
+
+pair<uint64_t, uint64_t> split(uint64_t a) {
+	int digits = 0;
+	for (uint64_t b = a; b != 0; b /= 10)
+		digits++;
+
+	if (digits % 2 == 1)
+		return make_pair(0, 0);
+
+	uint64_t j = 1;
+	for (int k = 0; k < digits/2; k++)
+		j *= 10;
+
+	return make_pair(a/j, a%j);
+}
+
+uint64_t count(uint64_t a, int n) {
+	if (n == 0)
+		return 1;
+
+	if (a == 0)
+		return count(1, n-1);
+
+	if (auto [x, y] = split(a); x != 0) {
+		auto c1 = count(x, n-1);
+		auto c2 = count(y, n-1);
+		return c1+c2;
+	}
+
+	return count(a*2024, n-1);
+}
+
+int main() {
+	uint64_t x;
+	vector<uint64_t> old, v;
+	while (cin >> x)
+		v.push_back(x);
+
+	uint64_t tot = 0;
+	for (auto a : v)
+		tot += count(a, 25);
+
+	cout << tot << endl;
+
+	return 0;
+}
diff --git a/2024/11/day11b.cpp b/2024/11/day11b.cpp
new file mode 100644
index 0000000..7f78e8e
--- /dev/null
+++ b/2024/11/day11b.cpp
@@ -0,0 +1,62 @@
+#include <algorithm>
+#include <cstdint>
+#include <iostream>
+#include <map>
+#include <ranges>
+#include <set>
+#include <sstream>
+#include <string>
+#include <string_view>
+#include <vector>
+using namespace std;
+
+map<pair<uint64_t, uint64_t>, uint64_t> t;
+
+pair<uint64_t, uint64_t> split(uint64_t a) {
+	int digits = 0;
+	for (uint64_t b = a; b != 0; b /= 10)
+		digits++;
+
+	if (digits % 2 == 1)
+		return make_pair(0, 0);
+
+	uint64_t j = 1;
+	for (int k = 0; k < digits/2; k++)
+		j *= 10;
+
+	return make_pair(a/j, a%j);
+}
+
+uint64_t count(uint64_t a, int n) {
+	if (n == 0)
+		return 1;
+
+	if (auto it = t.find(make_pair(a, n)); it != t.end())
+		return it->second;
+
+	if (a == 0)
+		return t[make_pair(a, n)] = count(1, n-1);
+
+	if (auto [x, y] = split(a); x != 0) {
+		auto c1 = count(x, n-1);
+		auto c2 = count(y, n-1);
+		return t[make_pair(a, n)] = c1+c2;
+	}
+
+	return t[make_pair(a, n)] = count(a*2024, n-1);
+}
+
+int main() {
+	uint64_t x;
+	vector<uint64_t> old, v;
+	while (cin >> x)
+		v.push_back(x);
+
+	uint64_t tot = 0;
+	for (auto a : v)
+		tot += count(a, 75);
+
+	cout << tot << endl;
+
+	return 0;
+}
diff --git a/2024/learned.txt b/2024/learned.txt
index 56fa515..440571a 100644
--- a/2024/learned.txt
+++ b/2024/learned.txt
@@ -8,3 +8,4 @@ List of things I learned (or refreshed) with this year's AoC.
 * Day 5: std::find and std::replace
 * Day 8: set::insert_range(), but it is from C++23 only
 * Day 9: std::views
+* Day 11: if(init; cond)
-- 
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