From b3bcb56b9ff48b78c7e1b5d6e9c38df44df7a049 Mon Sep 17 00:00:00 2001
From: Thomas Schmucker <ts@its1.de>
Date: Fri, 5 Jan 2024 00:19:27 +0100
Subject: solution for day 5

---
 2020/src/day05.cpp | 62 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 62 insertions(+)
 create mode 100644 2020/src/day05.cpp

(limited to '2020/src')

diff --git a/2020/src/day05.cpp b/2020/src/day05.cpp
new file mode 100644
index 0000000..1f5b797
--- /dev/null
+++ b/2020/src/day05.cpp
@@ -0,0 +1,62 @@
+#include <algorithm>
+#include <fstream>
+#include <iostream>
+#include <iterator>
+#include <string>
+#include <vector>
+#include <numeric>
+using namespace std;
+
+auto
+read_file(string_view filename)
+{
+	fstream input{ filename };
+	return vector<string>{ istream_iterator<string>{ input }, istream_iterator<string>{} };
+}
+
+auto
+to_int(string_view str)
+{
+	auto result = 0U;
+	for ( auto chr: str ) {
+		result <<= 1U;
+		if ( chr == 'B' || chr == 'R' ) {
+			result |= 1U;
+		}
+	}
+	return result;
+}
+
+void
+part1(const vector<string>& lines)
+{
+	auto value = 0U;
+	for ( const auto& line: lines ) {
+		value = max(value, to_int(line));
+	}
+	cout << value << endl;
+}
+
+void
+part2(const vector<string>& lines)
+{
+	vector<unsigned int> values;
+	transform(lines.begin(), lines.end(), back_inserter(values), to_int);
+
+	sort(values.begin(), values.end());
+
+	for ( size_t idx = 1; idx != values.size(); ++idx ) {
+		if ( values[idx - 1] != values[idx] - 1 ) {
+			cout << values[idx] - 1 << endl;
+			break;
+		}
+	}
+}
+
+int
+main()
+{
+	auto lines = read_file("data/day05.txt");
+	part1(lines);
+	part2(lines);
+}
-- 
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