Initial commit

2021-12-01 20:31:53 +00:00
commit 2f44ccc3a7
106 changed files with 9333 additions and 0 deletions
--- a/2020/puzzle-12-01.cc
+++ b/2020/puzzle-12-01.cc
@@ -0,0 +1,144 @@
+#include <algorithm>
+#include <array>
+#include <cassert>
+#include <iostream>
+#include <list>
+#include <map>
+#include <regex>
+#include <string>
+
+enum class Heading { North = 'N', East = 'E', South = 'S', West = 'W' };
+
+struct Position {
+  Position() : x_(0), y_(0), head_(Heading::East) {}
+
+  void move(std::string const &s) {
+    char act = s[0];
+    int dist = std::stoi(s.substr(1));
+
+    switch (act) {
+    case 'N':
+    case 'E':
+    case 'S':
+    case 'W':
+      move(dist, static_cast<Heading>(act));
+      break;
+    case 'F':
+      move(dist, head_);
+      break;
+    case 'L':
+      rotate_left(dist);
+      break;
+    case 'R':
+      rotate_left(360 - dist);
+      break;
+    default:
+      assert(false);
+    }
+
+    std::cout << s << ": (" << x_ << ", " << y_ << ")\n";
+  }
+
+  void move(int dist, Heading head) {
+    switch (head) {
+    case Heading::North:
+      y_ += dist;
+      break;
+    case Heading::East:
+      x_ += dist;
+      break;
+    case Heading::South:
+      y_ -= dist;
+      break;
+    case Heading::West:
+      x_ -= dist;
+      break;
+    default:
+      assert(false);
+      break;
+    }
+  }
+
+  void rotate_left(int deg) {
+    /* We want the rang [-180, 180]. */
+    while (deg < -180) {
+      deg += 360;
+    }
+    while (deg > 180) {
+      deg -= 360;
+    }
+
+    if (deg == -90) {
+      switch (head_) {
+      case Heading::North:
+        head_ = Heading::East;
+        break;
+      case Heading::East:
+        head_ = Heading::South;
+        break;
+      case Heading::South:
+        head_ = Heading::West;
+        break;
+      case Heading::West:
+        head_ = Heading::North;
+        break;
+      default:
+        assert(false);
+      }
+    } else if (deg == 90) {
+      switch (head_) {
+      case Heading::North:
+        head_ = Heading::West;
+        break;
+      case Heading::East:
+        head_ = Heading::North;
+        break;
+      case Heading::South:
+        head_ = Heading::East;
+        break;
+      case Heading::West:
+        head_ = Heading::South;
+        break;
+      default:
+        assert(false);
+      }
+    } else if (deg == 180 || deg == -180) {
+      switch (head_) {
+      case Heading::North:
+        head_ = Heading::South;
+        break;
+      case Heading::East:
+        head_ = Heading::West;
+        break;
+      case Heading::South:
+        head_ = Heading::North;
+        break;
+      case Heading::West:
+        head_ = Heading::East;
+        break;
+      default:
+        assert(false);
+      }
+    } else if (deg != 0) {
+      assert(false);
+    }
+  }
+
+  int distance() const noexcept { return std::abs(x_) + std::abs(y_); }
+
+  int x_;
+  int y_;
+  Heading head_;
+};
+
+int main(int argc, char **argv) {
+  Position pos;
+
+  for (std::string line; std::getline(std::cin, line);) {
+    pos.move(line);
+  }
+
+  auto dist = pos.distance();
+  std::cout << "Distance: " << dist << "\n";
+  return 0;
+}