From 93f9d02e978d10b4ff02ac029b6a6eff3d3193cf Mon Sep 17 00:00:00 2001
From: Sebastiano Tronto <sebastiano@tronto.net>
Date: Mon, 9 Dec 2024 06:36:25 +0100
Subject: Day 9 2024

---
 2024/09/Makefile   | 24 ++++++++++++++++++++++++
 2024/09/day09a.cpp | 32 ++++++++++++++++++++++++++++++++
 2024/09/day09b.cpp | 46 ++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 102 insertions(+)
 create mode 100644 2024/09/Makefile
 create mode 100644 2024/09/day09a.cpp
 create mode 100644 2024/09/day09b.cpp

(limited to '2024/09')

diff --git a/2024/09/Makefile b/2024/09/Makefile
new file mode 100644
index 0000000..89cd1b9
--- /dev/null
+++ b/2024/09/Makefile
@@ -0,0 +1,24 @@
+CC=g++ -std=c++20 -g -Wall
+
+a:
+	${CC} -o a.out day09a.cpp
+
+b:
+	${CC} -o b.out day09b.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/2024/09/day09a.cpp b/2024/09/day09a.cpp
new file mode 100644
index 0000000..c52c8f0
--- /dev/null
+++ b/2024/09/day09a.cpp
@@ -0,0 +1,32 @@
+#include <algorithm>
+#include <iostream>
+#include <map>
+#include <set>
+#include <sstream>
+#include <string>
+#include <string_view>
+#include <vector>
+using namespace std;
+
+int main() {
+	vector<long long> a;
+	char c;
+	for (int id = 0; cin >> c; id++)
+		for (int j = 0; j < c-'0'; j++)
+			a.push_back(id % 2 == 0 ? id/2 : -1); // -1 = space
+
+	int j = 0;
+	for (int i = a.size()-1; i >= 0; i--) {
+		while (a[j] >= 0) j++;
+		if (a[j] == -2) break;
+		a[j] = a[i];
+		a[i] = -2; // -2 = freed up
+	}
+
+	long long checksum = 0;
+	for (long long i = 0; i < (long long)a.size() && a[i] != -2; i++)
+		checksum += i*a[i];
+	cout << checksum << endl;
+
+	return 0;
+}
diff --git a/2024/09/day09b.cpp b/2024/09/day09b.cpp
new file mode 100644
index 0000000..3b1ac21
--- /dev/null
+++ b/2024/09/day09b.cpp
@@ -0,0 +1,46 @@
+#include <algorithm>
+#include <iostream>
+#include <map>
+#include <set>
+#include <sstream>
+#include <string>
+#include <string_view>
+#include <vector>
+using namespace std;
+
+int main() {
+	vector<long long> a;
+	vector<pair<int, int>> freesp, file;
+	char c;
+	for (int id = 0; cin >> c; id++) {
+		if (id % 2 == 1)
+			freesp.push_back(make_pair(a.size(), c-'0'));
+		else
+			file.push_back(make_pair(a.size(), c-'0'));
+		for (int j = 0; j < c-'0'; j++)
+			a.push_back(id % 2 == 0 ? id/2 : -1); // -1 = space
+	}
+
+	for (int i = file.size()-1; i >= 0; i--) {
+		for (auto& f : freesp) {
+			if (f.first >= file[i].first) break;
+			if (f.second >= file[i].second) {
+				for (int k = 0; k < file[i].second; k++) {
+					a[f.first+k] = a[file[i].first+k];
+					a[file[i].first+k] = -2;
+				}
+				f.first += file[i].second;
+				f.second -= file[i].second;
+				break;
+			}
+		}
+	}
+
+	long long checksum = 0;
+	for (long long i = 0; i < (long long)a.size(); i++)
+		if (a[i] >= 0)
+			checksum += i*a[i];
+	cout << checksum << endl;
+
+	return 0;
+}
-- 
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