From c8f0000c4db17305ca6404d7cc47803482f4d642 Mon Sep 17 00:00:00 2001
From: Thraix <thraix@hotmail.com>
Date: Thu, 6 Aug 2026 22:17:35 +0200
Subject: [PATCH] Add solution for 2016 Day 1

---
 res/2016/day01/test_input.txt |  2 +-
 src/2016/Day01.cpp            | 58 ++++++++++++++++++++++++++++++-----
 src/common/lib/Array2D.h      | 14 +++++++++
 3 files changed, 65 insertions(+), 9 deletions(-)

diff --git a/res/2016/day01/test_input.txt b/res/2016/day01/test_input.txt
index 00c8c89..1d6615f 100644
--- a/res/2016/day01/test_input.txt
+++ b/res/2016/day01/test_input.txt
@@ -1 +1 @@
-R5, L5, R5, R3
+R8, R4, R4, R8
diff --git a/src/2016/Day01.cpp b/src/2016/Day01.cpp
index 0189836..c7087b9 100644
--- a/src/2016/Day01.cpp
+++ b/src/2016/Day01.cpp
@@ -2,30 +2,72 @@
 
 namespace y2016::day01
 {
-  REGISTER_DAY(2016, Day01, std::vector<int>, int);
+  struct Move
+  {
+    char r;
+    int count;
+  };
 
-  REGISTER_TEST_EXAMPLE(2016, Day01, ExampleInput, 1, 0);
-  REGISTER_TEST(2016, Day01, Input, 1, 0);
-  REGISTER_TEST_EXAMPLE(2016, Day01, ExampleInput, 2, 0);
-  REGISTER_TEST(2016, Day01, Input, 2, 0);
+  REGISTER_DAY(2016, Day01, std::vector<Move>, int);
+
+  REGISTER_TEST_EXAMPLE(2016, Day01, ExampleInput, 1, 8);
+  REGISTER_TEST(2016, Day01, Input, 1, 271);
+  REGISTER_TEST_EXAMPLE(2016, Day01, ExampleInput, 2, 4);
+  REGISTER_TEST(2016, Day01, Input, 2, 153);
 
   READ_INPUT(input)
   {
-    std::vector<int> vec;
+    std::vector<Move> vec;
     std::string str;
-    while (getline(input, str))
+    while (getline(input, str, ' '))
     {
+      Move move;
+      move.r = str[0];
+      move.count = std::strtol(&str[1], nullptr, 10);
+      vec.emplace_back(move);
     }
     return vec;
   }
 
   OUTPUT1(input)
   {
-    return 0;
+    Index2D dir{1, 0};
+    Index2D pos{0, 0};
+    for (int i = 0; i < input.size(); i++)
+    {
+      if (input[i].r == 'R')
+        dir.RotateCW();
+      else
+        dir.RotateCCW();
+
+      pos = pos + dir * input[i].count;
+    }
+    return Helper::ManhattanDistance(pos, Index2D{0, 0});
   }
 
   OUTPUT2(input)
   {
+    Index2D dir{1, 0};
+    Index2D pos{0, 0};
+    std::set<Index2D> visited;
+    visited.emplace(pos);
+    for (int i = 0; i < input.size(); i++)
+    {
+      if (input[i].r == 'R')
+        dir.RotateCW();
+      else
+        dir.RotateCCW();
+
+      for (int j = 0; j < input[i].count; j++)
+      {
+        pos = pos + dir;
+        if (visited.count(pos) != 0)
+        {
+          return Helper::ManhattanDistance(pos, Index2D{0, 0});
+        }
+        visited.emplace(pos);
+      }
+    }
     return 0;
   }
 }
diff --git a/src/common/lib/Array2D.h b/src/common/lib/Array2D.h
index 88c6ba9..fde1f5d 100644
--- a/src/common/lib/Array2D.h
+++ b/src/common/lib/Array2D.h
@@ -9,6 +9,20 @@ struct Index2D
   int x = -1;
   int y = -1;
 
+  void RotateCW()
+  {
+    int tmp = y;
+    y = x;
+    x = -tmp;
+  }
+
+  void RotateCCW()
+  {
+    int tmp = y;
+    y = -x;
+    x = tmp;
+  }
+
   bool IsValid()
   {
     return x != -1 && y != -1;