1 files changed, 58 insertions, 0 deletions

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);
+}