From 543172da0e924c7efa34ef930d0592a7cde2701b Mon Sep 17 00:00:00 2001
From: Sebastian Lukas <sebastian.lukas@pionix.de>
Date: Thu, 26 Jan 2023 09:23:39 +0100
Subject: [PATCH] Solution for 2015 Day 5 part 2 (C++)

Signed-off-by: Sebastian Lukas <sebastian.lukas@pionix.de>
---
 2015/Day5/day5.cpp | 54 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 54 insertions(+)

diff --git a/2015/Day5/day5.cpp b/2015/Day5/day5.cpp
index 70e923e..95f1d8f 100644
--- a/2015/Day5/day5.cpp
+++ b/2015/Day5/day5.cpp
@@ -71,8 +71,62 @@ void part1() {
     std::cout << "Nice Strings: " << nice_strings << "\n";
 }
 
+bool check_xyy(std::string line) {
+    for (std::string::size_type i = 0; i < line.size()-2; i++) {
+        if (line[i] == line[i+2]) {
+            return true;
+        }
+    }
+    return false;
+}
+
+bool find_pair_of_2_letters(std::string line) {
+
+    std::string letters;
+    int found_letters = 0;
+    std::string::size_type start_pos = 0;
+
+    for (std::string::size_type i = 0; i < line.size()-2; i++) {
+        letters = line.substr(i, 2);
+
+        while (std::string::npos != (start_pos = line.find(letters, start_pos))) {
+            start_pos+=2;
+            found_letters++;
+            if (found_letters >= 2) return true;
+        }
+        start_pos = 0;
+        found_letters = 0;
+    }
+    return false;
+}
+
+void part2() {
+
+    std::ifstream input {"input.txt"};
+    std::string line;
+    int nice_strings = 0;
+
+    if (input.good()) {
+        while (input >> line) {
+
+            if (check_xyy(line) == false) {
+                continue;
+            }
+
+            if (find_pair_of_2_letters(line) == false) {
+                continue;
+            }
+            nice_strings++;
+        }
+    }
+    std::cout << "Nice Strings: " << nice_strings << "\n";
+
+}
+
 int main() {
 
     part1();
 
+    part2();
+
 }
\ No newline at end of file