From 5b3cfac3c45e4b1aa6cd95dfc6fd1bf0a6ab7ecd Mon Sep 17 00:00:00 2001
From: Matthew Gretton-Dann <matt@gretton-dann.org.uk>
Date: Wed, 13 Dec 2023 09:06:19 +0000
Subject: [PATCH] 2023 Day 13 Part 1

And optimized.
---
 2023/puzzle-13-01.cc | 74 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 74 insertions(+)
 create mode 100644 2023/puzzle-13-01.cc

diff --git a/2023/puzzle-13-01.cc b/2023/puzzle-13-01.cc
new file mode 100644
index 0000000..e26cd99
--- /dev/null
+++ b/2023/puzzle-13-01.cc
@@ -0,0 +1,74 @@
+#include <cstdint>
+#include <cstdlib>
+#include <iostream>
+#include <string>
+#include <vector>
+
+using UInt = std::uint64_t;
+
+struct Grid
+{
+  void clear() { rows_.clear(); }
+  void push_back(std::string const& row) { rows_.push_back(row); }
+
+  [[nodiscard]] auto reflection_point() -> UInt
+  {
+    for (std::size_t row{0}; row < rows_.size() - 1; ++row) {
+      auto top{row};
+      auto bottom{row + 1};
+      while (rows_[top] == rows_[bottom]) {
+        if (top == 0 || bottom == rows_.size() - 1) { return row + 1; }
+        --top;
+        ++bottom;
+      }
+    }
+
+    return 0;
+  }
+
+  [[nodiscard]] auto rotate_right() const -> Grid
+  {
+    Grid new_grid;
+    new_grid.rows_.resize(rows_.front().size());
+    for (auto row{rows_.rbegin()}; row != rows_.rend(); ++row) {
+      for (std::size_t i{0}; i < row->size(); ++i) {
+        new_grid.rows_[i].push_back(row->at(i));
+      }
+    }
+
+    return new_grid;
+  }
+
+private:
+  std::vector<std::string> rows_;
+};
+
+auto main() -> int try {
+  std::string line;
+
+  Grid grid;
+  UInt rows{0};
+  UInt cols{0};
+  while (std::getline(std::cin, line)) {
+    if (line.empty()) {
+      rows += grid.reflection_point();
+      grid = grid.rotate_right();
+      cols += grid.reflection_point();
+      grid.clear();
+    }
+    else { grid.push_back(line); }
+  }
+
+  rows += grid.reflection_point();
+  grid = grid.rotate_right();
+  cols += grid.reflection_point();
+
+  std::cout << "Columns to left: " << cols << '\n' << "Rows above: " << rows << '\n' << "Score: " <<
+    cols + (rows * 100) << '\n';
+
+  return EXIT_SUCCESS;
+}
+catch (...) {
+  std::cerr << "Uncaught exception.\n";
+  return EXIT_FAILURE;
+}