Add 2016 Day 2 puzzles

2016/puzzle-02-01.cc

@@ -0,0 +1,39 @@
+//
+// Created by Matthew Gretton-Dann on 03/12/2021.
+//
+#include <array>
+#include <iostream>
+#include <string>
+
+int main()
+{
+  constexpr std::array<unsigned, 10> down{0, 4, 5, 6, 7, 8, 9, 7, 8, 9};
+  constexpr std::array<unsigned, 10> left{0, 1, 1, 2, 4, 4, 5, 7, 7, 8};
+  constexpr std::array<unsigned, 10> up{0, 1, 2, 3, 1, 2, 3, 4, 5, 6};
+  constexpr std::array<unsigned, 10> right{0, 2, 3, 3, 5, 6, 6, 8, 9, 9};
+  unsigned pos{5};
+  std::string line;
+  std::string result;
+  while (std::getline(std::cin, line)) {
+    for (auto c : line) {
+      switch (c) {
+      case 'L':
+        pos = left[pos];
+        break;
+      case 'D':
+        pos = down[pos];
+        break;
+      case 'R':
+        pos = right[pos];
+        break;
+      case 'U':
+        pos = up[pos];
+        break;
+      default:
+        abort();
+      }
+    }
+    result += static_cast<char>('0' + pos);
+  }
+  std::cout << result << '\n';
+}

2016/puzzle-02-02.cc

@@ -0,0 +1,40 @@
+//
+// Created by Matthew Gretton-Dann on 03/12/2021.
+//
+#include <array>
+#include <iostream>
+#include <string>
+
+int main()
+{
+  constexpr std::array<unsigned, 14> down{0, 3, 6, 7, 8, 5, 10, 11, 12, 9, 10, 13, 12, 13};
+  constexpr std::array<unsigned, 14> left{0, 1, 2, 2, 3, 5, 5, 6, 7, 8, 10, 10, 11, 13};
+  constexpr std::array<unsigned, 14> up{0, 1, 2, 1, 4, 5, 2, 3, 4, 9, 6, 7, 8, 11};
+  constexpr std::array<unsigned, 14> right{0, 1, 3, 4, 4, 6, 7, 8, 9, 9, 11, 12, 12, 13};
+  const std::string_view letters{"0123456789ABCD"};
+  unsigned pos{5};
+  std::string line;
+  std::string result;
+  while (std::getline(std::cin, line)) {
+    for (auto c : line) {
+      switch (c) {
+      case 'L':
+        pos = left[pos];
+        break;
+      case 'D':
+        pos = down[pos];
+        break;
+      case 'R':
+        pos = right[pos];
+        break;
+      case 'U':
+        pos = up[pos];
+        break;
+      default:
+        abort();
+      }
+    }
+    result += letters[pos];
+  }
+  std::cout << result << '\n';
+}