From 85f5de1be29f3e4d21d9bcfc6a48855a12effb5f Mon Sep 17 00:00:00 2001
From: Thraix <thraix@hotmail.com>
Date: Mon, 31 Aug 2026 22:21:13 +0200
Subject: [PATCH] Add solution for 2016 Day 19

---
 res/2016/day19/test_input.txt |  1 +
 src/2016/Day19.cpp            | 64 ++++++++++++++++++++++++++++-------
 src/common/lib/Helper.h       | 10 ++++++
 3 files changed, 62 insertions(+), 13 deletions(-)

diff --git a/res/2016/day19/test_input.txt b/res/2016/day19/test_input.txt
index e69de29..7ed6ff8 100644
--- a/res/2016/day19/test_input.txt
+++ b/res/2016/day19/test_input.txt
@@ -0,0 +1 @@
+5
diff --git a/src/2016/Day19.cpp b/src/2016/Day19.cpp
index 6cd7d68..8d9a37c 100644
--- a/src/2016/Day19.cpp
+++ b/src/2016/Day19.cpp
@@ -2,30 +2,68 @@
 
 namespace y2016::day19
 {
-  REGISTER_DAY(2016, Day19, std::vector<int>, int);
+  REGISTER_DAY(2016, Day19, int, int);
 
-  REGISTER_TEST_EXAMPLE(2016, Day19, ExampleInput, 1, 0);
-  REGISTER_TEST(2016, Day19, Input, 1, 0);
-  REGISTER_TEST_EXAMPLE(2016, Day19, ExampleInput, 2, 0);
-  REGISTER_TEST(2016, Day19, Input, 2, 0);
+  REGISTER_TEST_EXAMPLE(2016, Day19, ExampleInput, 1, 3);
+  REGISTER_TEST(2016, Day19, Input, 1, 1842613);
+  REGISTER_TEST_EXAMPLE(2016, Day19, ExampleInput, 2, 2);
+  REGISTER_TEST(2016, Day19, Input, 2, 1424135);
 
   READ_INPUT(input)
   {
-    std::vector<int> vec;
-    std::string str;
-    while (getline(input, str))
-    {
-    }
-    return vec;
+    int i;
+    input >> i;
+    return i;
   }
 
   OUTPUT1(input)
   {
-    return 0;
+    std::vector<int> elves(input, 0);
+    for (int i = 0; i < input; i++)
+    {
+      elves[i] = i + 1;
+    }
+    int offset = 0;
+    while (elves.size() > 1)
+    {
+      std::vector<int> newElves;
+      for (int i = offset; i < elves.size(); i += 2)
+      {
+        newElves.emplace_back(elves[i]);
+      }
+      offset = (offset + (elves.size() % 2)) % 2;
+      elves = newElves;
+    }
+    return elves[0];
   }
 
   OUTPUT2(input)
   {
-    return 0;
+    std::deque<int> start;
+    std::deque<int> end;
+    for (int i = 0; i < input / 2; i++)
+    {
+      start.push_back(i + 1);
+    }
+    for (int i = input / 2; i < input; i++)
+    {
+      end.push_back(i + 1);
+    }
+
+    while (!start.empty())
+    {
+      end.pop_front();
+
+      end.push_back(start.front());
+      start.pop_front();
+
+      if (end.size() - start.size() == 2)
+      {
+        start.push_back(end.front());
+        end.pop_front();
+      }
+    }
+
+    return end.front();
   }
 }
diff --git a/src/common/lib/Helper.h b/src/common/lib/Helper.h
index ac090c9..6aeb4a1 100644
--- a/src/common/lib/Helper.h
+++ b/src/common/lib/Helper.h
@@ -4,6 +4,7 @@
 
 #include <algorithm>
 #include <array>
+#include <deque>
 #include <functional>
 #include <iostream>
 #include <limits>
@@ -20,6 +21,9 @@
 template <typename... Args>
 static std::ostream& operator<<(std::ostream& stream, const std::vector<Args...>& container);
 
+template <typename... Args>
+static std::ostream& operator<<(std::ostream& stream, const std::deque<Args...>& container);
+
 template <typename... Args>
 static std::ostream& operator<<(std::ostream& stream, const std::set<Args...>& container);
 
@@ -564,6 +568,12 @@ static std::ostream& operator<<(std::ostream& stream, const std::vector<Args...>
   return Helper::Print(stream, container);
 }
 
+template <typename... Args>
+static std::ostream& operator<<(std::ostream& stream, const std::deque<Args...>& container)
+{
+  return Helper::Print(stream, container);
+}
+
 template <typename... Args>
 static std::ostream& operator<<(std::ostream& stream, const std::set<Args...>& container)
 {