From da983a93216be3d7d94257f57e0419ce19159366 Mon Sep 17 00:00:00 2001
From: Matthew Gretton-Dann <matt@gretton-dann.org.uk>
Date: Fri, 17 Dec 2021 11:41:53 +0000
Subject: [PATCH] Add 2017 day 19 puzzles

---
 2017/puzzle-19-01.cc | 54 +++++++++++++++++++++++++++++++++++++++++
 2017/puzzle-19-02.cc | 57 ++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 111 insertions(+)
 create mode 100644 2017/puzzle-19-01.cc
 create mode 100644 2017/puzzle-19-02.cc

diff --git a/2017/puzzle-19-01.cc b/2017/puzzle-19-01.cc
new file mode 100644
index 0000000..b5204d0
--- /dev/null
+++ b/2017/puzzle-19-01.cc
@@ -0,0 +1,54 @@
+#include <cassert>
+#include <iostream>
+#include <string>
+#include <vector>
+
+using Map = std::vector<std::string>;
+
+auto main() -> int
+{
+  std::string line;
+  Map map;
+  std::size_t len{0};
+  while (std::getline(std::cin, line) && !line.empty()) {
+    len = std::max(line.size() + 1, len);
+    map.push_back(line);
+  }
+  for (auto& l : map) {
+    l.resize(len, ' ');
+  }
+  map.push_back(std::string(len, ' '));
+
+  int dx{0};
+  int dy{1};
+  auto x{map[0].find('|')};
+  decltype(x) y{0};
+  assert(x != std::string::npos);
+  std::string letters;
+
+  while (true) {
+    switch (map[y][x]) {
+    case '|':
+    case '-':
+      break;
+    case ' ':
+      std::cout << "Letters: " << letters << '\n';
+      return 0;
+    case '+':
+      if (dx != 0) {
+        dx = 0;
+        dy = (map[y + 1][x] != ' ') ? 1 : -1;
+      }
+      else {
+        dy = 0;
+        dx = (map[y][x + 1] != ' ') ? 1 : -1;
+      }
+      break;
+    default:
+      letters += map[y][x];
+      break;
+    }
+    x += dx;
+    y += dy;
+  }
+}
diff --git a/2017/puzzle-19-02.cc b/2017/puzzle-19-02.cc
new file mode 100644
index 0000000..d536347
--- /dev/null
+++ b/2017/puzzle-19-02.cc
@@ -0,0 +1,57 @@
+#include <cassert>
+#include <iostream>
+#include <string>
+#include <vector>
+
+using Map = std::vector<std::string>;
+
+auto main() -> int
+{
+  std::string line;
+  Map map;
+  std::size_t len{0};
+  while (std::getline(std::cin, line) && !line.empty()) {
+    len = std::max(line.size() + 1, len);
+    map.push_back(line);
+  }
+  for (auto& l : map) {
+    l.resize(len, ' ');
+  }
+  map.push_back(std::string(len, ' '));
+
+  int dx{0};
+  int dy{1};
+  auto x{map[0].find('|')};
+  decltype(x) y{0};
+  assert(x != std::string::npos);
+  std::string letters;
+  std::size_t moves{0};
+
+  while (true) {
+    switch (map[y][x]) {
+    case '|':
+    case '-':
+      break;
+    case ' ':
+      std::cout << "Letters: " << letters << '\n';
+      std::cout << "Moves: " << moves << '\n';
+      return 0;
+    case '+':
+      if (dx != 0) {
+        dx = 0;
+        dy = (map[y + 1][x] != ' ') ? 1 : -1;
+      }
+      else {
+        dy = 0;
+        dx = (map[y][x + 1] != ' ') ? 1 : -1;
+      }
+      break;
+    default:
+      letters += map[y][x];
+      break;
+    }
+    x += dx;
+    y += dy;
+    ++moves;
+  }
+}