aoc24: day06a complete

sol/24/day06.cpp

@@ -1,7 +1,149 @@
+#include <vector>
+#include <algorithm>
+#include <ranges>
+#include <numeric>
+#include <cmath>
+#include <utility>
+
 #include "aoc.hpp"
 #include "aoc/utils.hpp"
 #include "fmt/format.h"
 
-auto aoc24::day06([[maybe_unused]]std::span<char const*> const& args) -> std::expected<void, aoc::error> {
-    return aoc::make_error("day 5", std::errc::not_supported);
+using namespace std::string_view_literals;
+using namespace aoc::types;
+
+namespace lab {
+
+class guard {
+public:
+    guard(i64 x, i64 y) : m_row(y), m_col(x) { }
+
+    auto set_direction(i64 x, i64 y) -> void {
+        m_dx = x;
+        m_dy = y;
+    }
+    auto set_dx(i64 x) -> void { m_dx = x; }
+    auto set_dy(i64 y) -> void { m_dy = y; }
+    auto set_x(i64 v) -> void { m_col = v; }
+    auto set_y(i64 v) -> void { m_row = v; }
+    auto x() const -> i64 { return m_col; }
+    auto y() const -> i64 { return m_row; }
+    auto dx() const -> i64 { return m_dx; }
+    auto dy() const -> i64 { return m_dy; }
+
+    auto move() -> void {
+        m_row += m_dy;
+        m_col += m_dx;
+    }
+
+private:
+    i64 m_row;
+    i64 m_col;
+    i64 m_dx;
+    i64 m_dy;
+};
+
+class lab {
+public:
+    lab(std::string const& map_str) {
+        auto const lines = map_str
+                         | std::views::split("\n"sv)
+                         | std::views::transform([](auto const& str) {
+                               return std::string_view(std::begin(str), std::end(str));
+                         })
+                         | std::views::filter([](auto const& str) { return !str.empty(); })
+                         | std::views::transform([](auto const& str) {
+                               return str | std::views::filter([](auto const& ch) { return ch != '\n'; })
+                                          | std::ranges::to<std::vector>();
+                         }) | std::ranges::to<std::vector>();
+
+        m_rows = lines.size();
+        m_cols = lines[0].size();
+        std::ranges::for_each(lines, [&](auto const& str) {
+            std::ranges::for_each(str, [&](auto const& ch) {
+                m_data.emplace_back(ch);
+            });
+        });
+
+        auto it = std::find_if(std::begin(m_data), std::end(m_data), [](auto const ch) { return ch == '^'; });
+        if (it != std::end(m_data)) m_start.set_direction(0, -1);
+
+        auto const dist = usize(it - std::begin(m_data));
+        m_start.set_x(i64(dist - (dist / m_cols * m_rows)));
+        m_start.set_y(i64(dist / m_cols));
+    }
+
+    auto start() const -> guard { return m_start; }
+    auto rows() const -> usize { return m_rows; }
+    auto cols() const -> usize { return m_cols; }
+
+    auto is_obstruction(usize x, usize y) const -> bool {
+        if (x >= m_cols || y >= m_rows) return false;
+        return m_data[y * m_cols + x] == '#';
+    }
+
+    auto is_obstruction(guard const& g) const -> bool {
+        return is_obstruction(usize(g.x()), usize(g.y()));
+    }
+
+    auto is_outside(usize x, usize y) const -> bool {
+        return x >= m_cols || y >= m_rows;
+    }
+
+    auto is_outside(guard const& g) const -> bool {
+        return is_outside(usize(g.x()), usize(g.y()));
+    }
+
+private:
+    usize m_rows{};
+    usize m_cols{};
+    std::vector<u8> m_data{};
+    guard           m_start{0, 0};
+};
+}
+
+auto part_a(lab::lab const& map) -> void {
+    // for (usize i = 0; i < map.rows; ++i) {
+    //     for (usize j = 0; j < map.cols; ++j) {
+    //         fmt::print("{} ", c8(map.data[i * map.cols + j]));
+    //     }
+    //     fmt::print("\n");
+    // }
+    std::vector<u8> cpy{};
+    cpy.resize(map.rows() * map.cols());
+    std::fill(std::begin(cpy), std::end(cpy), 0);
+
+    auto guard = map.start();
+
+    while (!map.is_outside(guard)) {
+        cpy[usize(guard.y()) * map.cols() + usize(guard.x())] = 1;
+        lab::guard guard_cpy = guard;
+        guard_cpy.move();
+
+        if (map.is_obstruction(guard_cpy)) {
+            if (guard_cpy.dy() == -1)
+                guard.set_direction(1, 0);
+            else if (guard_cpy.dy() == 1)
+                guard.set_direction(-1, 0);
+            else if (guard_cpy.dx() == -1)
+                guard.set_direction(0, -1);
+            else if (guard_cpy.dx() == 1)
+                guard.set_direction(0, 1);
+        }
+        guard.move();
+    }
+
+    auto const sum = std::accumulate(std::begin(cpy), std::end(cpy), 0);
+    fmt::print("Part A: {}\n", sum);
+}
+
+auto aoc24::day06([[maybe_unused]]std::span<char const*> const& args) -> std::expected<void, aoc::error> {
+    auto res = aoc::read_text("./dat/24/re/06.txt");
+    if (!res) return std::unexpected(res.error());
+    auto const map_txt = *res;
+
+    lab::lab map{map_txt};
+    part_a(map);
+
+    return {};
 }