From bec8be80a3d2db40c28c705cf55e8a3565a3adcc Mon Sep 17 00:00:00 2001
From: Thraix <thraix@hotmail.com>
Date: Fri, 4 Sep 2026 18:37:13 +0200
Subject: [PATCH] Add solution for 2016 Day 22

---
 res/2016/day22/test_input.txt |  11 ++++
 src/2016/Day22.cpp            | 121 +++++++++++++++++++++++++++++++---
 src/common/lib/Array2D.h      |   5 ++
 3 files changed, 129 insertions(+), 8 deletions(-)

diff --git a/res/2016/day22/test_input.txt b/res/2016/day22/test_input.txt
index e69de29..7793929 100644
--- a/res/2016/day22/test_input.txt
+++ b/res/2016/day22/test_input.txt
@@ -0,0 +1,11 @@
+root@ebhq-gridcenter# df -h
+Filesystem            Size  Used  Avail  Use%
+/dev/grid/node-x0-y0   10T    8T     2T   80%
+/dev/grid/node-x0-y1   11T    6T     5T   54%
+/dev/grid/node-x0-y2   32T   28T     4T   87%
+/dev/grid/node-x1-y0    9T    7T     2T   77%
+/dev/grid/node-x1-y1    8T    0T     8T    0%
+/dev/grid/node-x1-y2   11T    7T     4T   63%
+/dev/grid/node-x2-y0   10T    6T     4T   60%
+/dev/grid/node-x2-y1    9T    8T     1T   88%
+/dev/grid/node-x2-y2    9T    6T     3T   66%
diff --git a/src/2016/Day22.cpp b/src/2016/Day22.cpp
index 472b6b4..d92d364 100644
--- a/src/2016/Day22.cpp
+++ b/src/2016/Day22.cpp
@@ -2,30 +2,135 @@
 
 namespace y2016::day22
 {
-  REGISTER_DAY(2016, Day22, std::vector<int>, int);
+  struct Fs
+  {
+    int used;
+    int avail;
 
-  REGISTER_TEST_EXAMPLE(2016, Day22, ExampleInput, 1, 0);
-  REGISTER_TEST(2016, Day22, Input, 1, 0);
-  REGISTER_TEST_EXAMPLE(2016, Day22, ExampleInput, 2, 0);
-  REGISTER_TEST(2016, Day22, Input, 2, 0);
+    bool operator==(const Fs& other) const
+    {
+      return used == other.used && avail == other.avail;
+    }
+  };
+
+  REGISTER_DAY(2016, Day22, Array2D<Fs>, int);
+
+  REGISTER_TEST_EXAMPLE(2016, Day22, ExampleInput, 1, 7);
+  REGISTER_TEST(2016, Day22, Input, 1, 1024);
+  REGISTER_TEST_EXAMPLE(2016, Day22, ExampleInput, 2, 7);
+  REGISTER_TEST(2016, Day22, Input, 2, 230);
 
   READ_INPUT(input)
   {
-    std::vector<int> vec;
+    std::vector<std::pair<std::pair<int, int>, Fs>> fss;
+    Array2D<Fs> vec{};
     std::string str;
+    getline(input, str);
+    getline(input, str);
+    int maxX = 0;
+    int maxY = 0;
     while (getline(input, str))
     {
+      // /dev/grid/node-x0-y0     91T   71T    20T   78%
+      Fs fs;
+      std::stringstream ss{str};
+      int dummy;
+      int x;
+      int y;
+      ss >> "/dev/grid/node-x" >> x >> "-y" >> y >> dummy >> "T" >> fs.used >> "T" >> fs.avail >> "T";
+      fss.emplace_back(std::pair{std::pair{x, y}, fs});
+      maxX = std::max(maxX, x);
+      maxY = std::max(maxY, y);
+    }
+    vec = Array2D<Fs>{maxX + 1, maxY + 1};
+    for (const auto& [pos, fs] : fss)
+    {
+      vec.Set(pos.first, pos.second, fs);
     }
     return vec;
   }
 
+  struct State
+  {
+    Index2D goal;
+    Index2D empty;
+
+    bool operator<(const State& other) const
+    {
+      if (goal != other.goal)
+        return goal < other.goal;
+      return empty < other.empty;
+    }
+
+    friend std::ostream& operator<<(std::ostream& os, const State& state)
+    {
+      return os << state.goal << " " << state.empty;
+    }
+  };
+
+  std::vector<std::pair<int, State>> Branch(const Array2D<Fs>& initial, const State& state)
+  {
+    std::vector<std::pair<int, State>> states{};
+    Fs emptyFs = initial.Get(state.empty);
+    std::vector<Index2D> neighbors = initial.GetNeighbors(state.empty, false);
+    for (const auto& neighbor : neighbors)
+    {
+      if (initial.Get(neighbor).used < 400)
+      {
+        State newState = state;
+        if (neighbor == state.goal)
+          newState.goal = state.empty;
+        newState.empty = neighbor;
+        states.emplace_back(1, newState);
+      }
+    }
+    return states;
+  }
+
+  bool Goal(const Array2D<Fs>& initial, const State& state)
+  {
+    return state.goal == Index2D{0, 0};
+  }
+
+  int Heuristic(const Array2D<Fs>& initial, const State& state)
+  {
+    return state.goal.x + state.goal.y;
+  }
+
   OUTPUT1(input)
   {
-    return 0;
+    int count = 0;
+    for (const auto& val : input)
+    {
+      if (val.used == 0)
+        continue;
+      for (const auto& val2 : input)
+      {
+        if (val == val2)
+          continue;
+        if (val.used <= val2.avail)
+        {
+          count++;
+        }
+      }
+    }
+    return count;
   }
 
   OUTPUT2(input)
   {
-    return 0;
+    State state;
+    state.goal = Index2D{input.width - 1, 0};
+    for (int i = 0; i < input.height; i++)
+    {
+      for (int j = 0; j < input.width; j++)
+      {
+        if (input.Get(j, i).used == 0)
+        {
+          state.empty = Index2D{j, i};
+        }
+      }
+    }
+    return Helper::AStar(input, state, Heuristic, Branch, Goal);
   }
 }
diff --git a/src/common/lib/Array2D.h b/src/common/lib/Array2D.h
index 366cf63..19e0fdc 100644
--- a/src/common/lib/Array2D.h
+++ b/src/common/lib/Array2D.h
@@ -500,6 +500,11 @@ struct Array2D
     return ConstIterator{*this, Index2D{0, height}};
   }
 
+  bool operator<(const Array2D<T>& other) const
+  {
+    return array2D < other.array2D;
+  }
+
   friend std::ostream& operator<<(std::ostream& os, const Array2D& array2D)
   {
     for (int y = 0; y < array2D.height; y++)