From 52ac586dcd7c78184d5884b0587f6b2c6fae98c4 Mon Sep 17 00:00:00 2001
From: Thomas Schmucker <ts@its1.de>
Date: Thu, 4 Jan 2024 00:32:07 +0100
Subject: solutions fpor day 1 & day 2, advent of code 2020

---
 2020/src/day01.cpp | 21 +++++++++++---------
 2020/src/day02.cpp | 58 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 70 insertions(+), 9 deletions(-)
 create mode 100644 2020/src/day02.cpp

(limited to '2020/src')

diff --git a/2020/src/day01.cpp b/2020/src/day01.cpp
index d2d8629..67f88c4 100644
--- a/2020/src/day01.cpp
+++ b/2020/src/day01.cpp
@@ -32,24 +32,27 @@ process(const vector<long>& values)
 void
 combination(const vector<long>& values, size_t r)
 {
-	vector<bool> v(values.size());
-	fill(v.end() - long(r), v.end(), true);
-	vector<long> set(r);
+	vector<bool> marker(values.size());
+
+	fill(marker.end() - long(r), marker.end(), true);
+
+	vector<long> subset(r);
+
 	do {
-		set.clear();
+		subset.clear();
 		for ( size_t i = 0; i != values.size(); ++i ) {
-			if ( v[i] ) {
-				set.emplace_back(values[i]);
+			if ( marker[i] ) {
+				subset.emplace_back(values[i]);
 			}
 		}
-		process(set);
-	} while ( std::next_permutation(v.begin(), v.end()) );
+		process(subset);
+	} while ( std::next_permutation(marker.begin(), marker.end()) );
 }
 
 int
 main()
 {
-	auto values = read_file("data/day01-sample1.txt");
+	auto values = read_file("data/day01.txt");
 	combination(values, 2);
 	combination(values, 3);
 }
diff --git a/2020/src/day02.cpp b/2020/src/day02.cpp
new file mode 100644
index 0000000..d7e28f1
--- /dev/null
+++ b/2020/src/day02.cpp
@@ -0,0 +1,58 @@
+#include <fstream>
+#include <functional>
+#include <iostream>
+#include <numeric>
+#include <string>
+#include <vector>
+using namespace std;
+
+auto
+read_file(string_view filename)
+{
+	fstream                                 input{ filename };
+	vector<tuple<long, long, char, string>> data;
+
+	for ( string line; getline(input, line); ) {
+		long min = 0;
+		long max = 0;
+		char chr = 0;
+		char password[100];
+		sscanf(line.data(), "%ld-%ld %c: %99s", &min, &max, &chr, password); // NOLINT
+		data.emplace_back(min, max, chr, password);
+	}
+
+	return data;
+}
+
+void
+part1(vector<tuple<long, long, char, string>>& data)
+{
+	long sum = 0;
+	for ( const auto& [min, max, chr, password]: data ) {
+		const auto amount = count(password.begin(), password.end(), chr);
+		if ( min <= amount && amount <= max ) {
+			++sum;
+		}
+	}
+	cout << sum << endl;
+}
+
+void
+part2(vector<tuple<long, long, char, string>>& data)
+{
+	long sum = 0;
+	for ( const auto& [min, max, chr, password]: data ) {
+		if ( (password[size_t(min - 1)] == chr) ^ (password[size_t(max - 1)] == chr) ) {
+			++sum;
+		}
+	}
+	cout << sum << endl;
+}
+
+int
+main()
+{
+	auto input = read_file("data/day02.txt");
+	part1(input);
+	part2(input);
+}
-- 
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