Add solution for 2016 Day 21

src/2016/Day21.cpp

@@ -2,30 +2,228 @@
 
 namespace y2016::day21
 {
-  REGISTER_DAY(2016, Day21, std::vector<int>, int);
+  enum class Operator
+  {
+    Swap,
+    SwapLetter,
+    Rotate,
+    RotatePos,
+    Reverse,
+    Move
+  };
 
-  REGISTER_TEST_EXAMPLE(2016, Day21, ExampleInput, 1, 0);
-  REGISTER_TEST(2016, Day21, Input, 1, 0);
-  REGISTER_TEST_EXAMPLE(2016, Day21, ExampleInput, 2, 0);
-  REGISTER_TEST(2016, Day21, Input, 2, 0);
+  struct Instruction
+  {
+    Operator op;
+    int arg1;
+    int arg2;
+  };
+
+  REGISTER_DAY(2016, Day21, std::vector<Instruction>, std::string);
+
+  REGISTER_TEST_EXAMPLE(2016, Day21, ExampleInput, 1, "decab");
+  REGISTER_TEST(2016, Day21, Input, 1, "hcdefbag");
+  REGISTER_TEST(2016, Day21, Input, 2, "fbhaegdc");
 
   READ_INPUT(input)
   {
-    std::vector<int> vec;
+    std::vector<Instruction> vec;
     std::string str;
     while (getline(input, str))
     {
+      Instruction instruction;
+      std::stringstream ss{str};
+      if (Helper::StartsWith(str, "swap position"))
+      {
+        instruction.op = Operator::Swap;
+        ss >> "swap position " >> instruction.arg1 >> "with position " >> instruction.arg2;
+      }
+      else if (Helper::StartsWith(str, "swap letter"))
+      {
+        instruction.op = Operator::SwapLetter;
+        char c1, c2;
+        ss >> "swap letter " >> c1 >> "with letter " >> c2;
+        instruction.arg1 = c1;
+        instruction.arg2 = c2;
+      }
+      else if (Helper::StartsWith(str, "rotate left"))
+      {
+        instruction.op = Operator::Rotate;
+        ss >> "rotate left" >> instruction.arg1;
+        instruction.arg1 = -instruction.arg1;
+      }
+      else if (Helper::StartsWith(str, "rotate right"))
+      {
+        instruction.op = Operator::Rotate;
+        ss >> "rotate right" >> instruction.arg1;
+      }
+      else if (Helper::StartsWith(str, "rotate based"))
+      {
+        instruction.op = Operator::RotatePos;
+        char c;
+        ss >> "rotate based on position of letter " >> c;
+        instruction.arg1 = c;
+      }
+      else if (str[0] == 'r')
+      {
+        instruction.op = Operator::Reverse;
+        ss >> "reverse positions " >> instruction.arg1 >> "through " >> instruction.arg2;
+      }
+      else
+      {
+        instruction.op = Operator::Move;
+        ss >> "move position " >> instruction.arg1 >> "to position " >> instruction.arg2;
+      }
+      vec.emplace_back(instruction);
     }
     return vec;
   }
 
   OUTPUT1(input)
   {
-    return 0;
+    CyclicVector<char> data{isExample ? "abcde" : "abcdefgh"};
+    for (const auto& instruction : input)
+    {
+      switch (instruction.op)
+      {
+        case Operator::Swap:
+        {
+          std::swap(data[instruction.arg1], data[instruction.arg2]);
+          break;
+        }
+        case Operator::SwapLetter:
+        {
+          size_t i1 = data.Find(instruction.arg1);
+          size_t i2 = data.Find(instruction.arg2);
+          std::swap(data[i1], data[i2]);
+          break;
+        }
+        case Operator::Rotate:
+        {
+          data.Rotate(instruction.arg1);
+          break;
+        }
+        case Operator::RotatePos:
+        {
+          size_t pos = data.Find(instruction.arg1);
+          int additional = pos >= 4 ? 1 : 0;
+          data.Rotate(pos + 1 + additional);
+          break;
+        }
+        case Operator::Reverse:
+        {
+          for (size_t i = 0; i < (instruction.arg2 - instruction.arg1 + 1) / 2; i++)
+          {
+            std::swap(data[instruction.arg1 + i], data[instruction.arg2 - i]);
+          }
+          break;
+        }
+        case Operator::Move:
+        {
+          if (instruction.arg1 < instruction.arg2)
+          {
+            char c = data[instruction.arg1];
+            for (size_t i = instruction.arg1; i < instruction.arg2; i++)
+            {
+              data[i] = data[i + 1];
+            }
+            data[instruction.arg2] = c;
+          }
+          else
+          {
+            char c = data[instruction.arg1];
+            for (size_t i = instruction.arg1; i > instruction.arg2; i--)
+            {
+              data[i] = data[i - 1];
+            }
+            data[instruction.arg2] = c;
+          }
+          break;
+        }
+      }
+    }
+    std::string str;
+    for (size_t i = 0; i < data.size(); i++)
+    {
+      str.push_back(data[i]);
+    }
+    return str;
   }
 
   OUTPUT2(input)
   {
-    return 0;
+    CyclicVector<char> data{"fbgdceah"};
+    std::map<int, int> rotatePosMap;
+    for (int i = 0; i < data.size(); i++)
+    {
+      int result = (i + i + 1 + (i >= 4 ? 1 : 0)) % data.size();
+      rotatePosMap.emplace(result, i - result);
+    }
+    for (int i = input.size() - 1; i >= 0; i--)
+    {
+      const auto& instruction = input[i];
+      switch (instruction.op)
+      {
+        case Operator::Swap:
+        {
+          std::swap(data[instruction.arg1], data[instruction.arg2]);
+          break;
+        }
+        case Operator::SwapLetter:
+        {
+          size_t i1 = data.Find(instruction.arg1);
+          size_t i2 = data.Find(instruction.arg2);
+          std::swap(data[i1], data[i2]);
+          break;
+        }
+        case Operator::Rotate:
+        {
+          data.Rotate(-instruction.arg1);
+          break;
+        }
+        case Operator::RotatePos:
+        {
+          size_t pos = data.Find(instruction.arg1);
+          data.Rotate(rotatePosMap[pos]);
+          break;
+        }
+        case Operator::Reverse:
+        {
+          for (size_t i = 0; i < (instruction.arg2 - instruction.arg1 + 1) / 2; i++)
+          {
+            std::swap(data[instruction.arg1 + i], data[instruction.arg2 - i]);
+          }
+          break;
+        }
+        case Operator::Move:
+        {
+          if (instruction.arg2 < instruction.arg1)
+          {
+            char c = data[instruction.arg2];
+            for (size_t i = instruction.arg2; i < instruction.arg1; i++)
+            {
+              data[i] = data[i + 1];
+            }
+            data[instruction.arg1] = c;
+          }
+          else
+          {
+            char c = data[instruction.arg2];
+            for (size_t i = instruction.arg2; i > instruction.arg1; i--)
+            {
+              data[i] = data[i - 1];
+            }
+            data[instruction.arg1] = c;
+          }
+          break;
+        }
+      }
+    }
+    std::string str;
+    for (auto c : data)
+    {
+      str.push_back(c);
+    }
+    return str;
   }
 }

src/common/aoc.h

@@ -24,6 +24,7 @@
 #include "common/lib/Array2D.h"
 #include "common/lib/Array3D.h"
 #include "common/lib/Array4D.h"
+#include "common/lib/CyclicVector.h"
 #include "common/lib/Graph.h"
 #include "common/lib/Helper.h"
 #include "common/lib/Input.h"

src/common/lib/CyclicVector.h

@@ -0,0 +1,354 @@
+#pragma once
+
+#include <ostream>
+#include <string>
+#include <vector>
+
+template <typename T>
+struct CyclicVector
+{
+  std::vector<T> vector;
+  size_t offset{0};
+
+  CyclicVector(const std::initializer_list<T>& vector)
+    : vector{vector}
+  {
+  }
+
+  CyclicVector(const std::vector<T>& vector)
+    : vector{vector}
+  {
+  }
+
+  template <typename U = T, typename = std::enable_if_t<std::is_same_v<U, char>>>
+  CyclicVector(const std::string& str)
+    : vector{str.begin(), str.end()}
+  {
+  }
+
+  template <std::size_t N, typename U = T, typename = std::enable_if_t<std::is_same_v<U, char>>>
+  CyclicVector(const char (&str)[N])
+  {
+    vector.resize(N - 1);  // don't include \0 character
+    for (size_t i = 0; i < N - 1; i++)
+    {
+      vector[i] = str[i];
+    }
+  }
+
+  void Rotate(int i)
+  {
+    if (i < 0)
+      RotateLeft(-i);
+    else
+      RotateRight(i);
+  }
+
+  void RotateRight(int i)
+  {
+    offset = (offset + vector.size() - (i % vector.size())) % vector.size();
+  }
+
+  void RotateLeft(size_t i)
+  {
+    offset = (offset + i) % vector.size();
+  }
+
+  T& operator[](size_t i)
+  {
+    return vector[(i + offset) % vector.size()];
+  }
+
+  const T& operator[](size_t i) const
+  {
+    return vector[(i + offset) % vector.size()];
+  }
+
+  size_t size() const
+  {
+    return vector.size();
+  }
+
+  bool empty() const
+  {
+    return vector.empty();
+  }
+
+  size_t Find(const T& t) const
+  {
+    return std::find(begin(), end(), t).GetPos();
+  }
+
+  struct iterator;
+  struct const_iterator;
+
+  iterator begin()
+  {
+    return iterator{*this, 0};
+  }
+
+  iterator end()
+  {
+    return iterator{*this, vector.size()};
+  }
+
+  const_iterator begin() const
+  {
+    return const_iterator{*this, 0};
+  }
+
+  const_iterator end() const
+  {
+    return const_iterator{*this, vector.size()};
+  }
+
+  const_iterator cbegin() const
+  {
+    return const_iterator{*this, 0};
+  }
+
+  const_iterator cend() const
+  {
+    return const_iterator{*this, vector.size()};
+  }
+
+  friend std::ostream& operator<<(std::ostream& os, const CyclicVector& vector)
+  {
+    os << "[";
+    if (!vector.empty())
+      os << vector[0];
+
+    for (auto it = vector.cbegin() + 1; it != vector.cend(); it++)
+    {
+      os << ", " << *it;
+    }
+    os << "]";
+    return os;
+  }
+
+  class iterator
+  {
+  private:
+    CyclicVector<T>& data;
+    size_t pos;
+
+  public:
+    using iterator_category = std::random_access_iterator_tag;
+    using value_type = T;
+    using difference_type = int;
+    using pointer = T*;
+    using reference = T&;
+
+    iterator(CyclicVector<T>& data, size_t pos)
+      : data{data},
+        pos{pos}
+    {
+    }
+
+    size_t GetPos() const
+    {
+      return pos;
+    }
+
+    reference operator*() const
+    {
+      return data[pos];
+    }
+
+    pointer operator->() const
+    {
+      return &data[pos];
+    }
+
+    iterator& operator++()
+    {
+      ++pos;
+      return *this;
+    }
+
+    iterator operator++(int)
+    {
+      iterator ret = *this;
+      ++(*this);
+      return ret;
+    }
+
+    iterator& operator--()
+    {
+      --pos;
+      return *this;
+    }
+
+    iterator operator--(int)
+    {
+      iterator ret = *this;
+      --(*this);
+      return ret;
+    }
+
+    iterator& operator+=(size_t advance)
+    {
+      if (std::numeric_limits<size_t>::max() - pos < advance)
+      {
+        pos = data.size();
+      }
+      else
+      {
+        pos += advance;
+        if (pos >= data.size())
+          pos = data.size();
+      }
+      return *this;
+    }
+
+    iterator& operator-=(size_t advance)
+    {
+      if (advance > pos)
+      {
+        pos = data.size();
+      }
+      else
+      {
+        pos -= advance;
+      }
+      return *this;
+    }
+
+    iterator operator+(size_t advance) const
+    {
+      iterator ret = *this;
+      ret += advance;
+      return ret;
+    }
+
+    iterator operator-(size_t advance) const
+    {
+      iterator ret = *this;
+      ret -= advance;
+      return ret;
+    }
+
+    bool operator==(const iterator& other) const
+    {
+      return pos == other.pos;
+    }
+
+    bool operator!=(const iterator& other) const
+    {
+      return !(*this == other);
+    }
+  };
+
+  class const_iterator
+  {
+  private:
+    const CyclicVector<T>& data;
+    size_t pos;
+
+  public:
+    using iterator_category = std::random_access_iterator_tag;
+    using value_type = T;
+    using difference_type = int;
+    using pointer = const T*;
+    using reference = const T&;
+
+    const_iterator(const CyclicVector<T>& data, size_t pos)
+      : data{data},
+        pos{pos}
+    {
+    }
+
+    size_t GetPos() const
+    {
+      return pos;
+    }
+
+    reference operator*() const
+    {
+      return data[pos];
+    }
+
+    pointer operator->() const
+    {
+      return &data[pos];
+    }
+
+    const_iterator& operator++()
+    {
+      ++pos;
+      return *this;
+    }
+
+    const_iterator operator++(int)
+    {
+      const_iterator ret = *this;
+      ++(*this);
+      return ret;
+    }
+
+    const_iterator& operator--()
+    {
+      --pos;
+      return *this;
+    }
+
+    const_iterator operator--(int)
+    {
+      const_iterator ret = *this;
+      --(*this);
+      return ret;
+    }
+
+    const_iterator& operator+=(size_t advance)
+    {
+      if (std::numeric_limits<size_t>::max() - pos < advance)
+      {
+        pos = data.size();
+      }
+      else
+      {
+        pos += advance;
+        if (pos >= data.size())
+          pos = data.size();
+      }
+      return *this;
+    }
+
+    const_iterator& operator-=(size_t advance)
+    {
+      if (advance > pos)
+      {
+        pos = data.size();
+      }
+      else
+      {
+        pos -= advance;
+      }
+      return *this;
+    }
+
+    const_iterator operator+(size_t advance) const
+    {
+      const_iterator ret = *this;
+      ret += advance;
+      return ret;
+    }
+
+    const_iterator operator-(size_t advance) const
+    {
+      const_iterator ret = *this;
+      ret -= advance;
+      return ret;
+    }
+
+    bool operator==(const const_iterator& other) const
+    {
+      return pos == other.pos;
+    }
+
+    bool operator!=(const const_iterator& other) const
+    {
+      return !(*this == other);
+    }
+  };
+};