aoc(2314): Parabolic Reflector Dish

4 files changed, 237 insertions, 0 deletions

diff --git a/2023/14/Makefile b/2023/14/Makefile
new file mode 100644
index 0000000..af6a294
--- /dev/null
+++ b/2023/14/Makefile
@@ -0,0 +1,19 @@
+CXXFLAGS := -std=c++17
+CPPFLAGS := -I../include
+EXE := part1 part2
+
+.PHONY: all clean configure
+
+all: $(EXE)
+
+configure:
+        bear -- $(MAKE) all
+
+%.o: %.cpp
+        $(CXX) -c $(CPPFLAGS) $(CXXFLAGS) $< -o $@
+
+clean:
+        rm -rf $(EXE) src/*.o compile_commands.json
+
+%: src/%.o
+        $(CXX) $^ -o $@
diff --git a/2023/14/resources/input_small.txt b/2023/14/resources/input_small.txt
new file mode 100644
index 0000000..5a24dce
--- /dev/null
+++ b/2023/14/resources/input_small.txt
@@ -0,0 +1,10 @@
+O....#....
+O.OO#....#
+.....##...
+OO.#O....O
+.O.....O#.
+O.#..O.#.#
+..O..#O..O
+.......O..
+#....###..
+#OO..#....
diff --git a/2023/14/src/part1.cpp b/2023/14/src/part1.cpp
new file mode 100644
index 0000000..c2179b7
--- /dev/null
+++ b/2023/14/src/part1.cpp
@@ -0,0 +1,41 @@
+#include <iostream>
+#include <fstream>
+#include <vector>
+
+std::vector<std::string> parse(const char* file)
+{
+    std::vector<std::string> v;
+    if (std::ifstream input{ file }; input.is_open())
+    {
+        std::string line;
+        while (not std::getline(input,line).eof())
+        {
+            v.push_back(std::move(line));
+        }
+    }
+    return v;
+}
+
+int main(int argc, char* argv[])
+{
+    int answer{};
+
+    auto v = parse(argv[1]);
+    for (int c = 0; c < v.size(); ++c)
+    {
+        int floor = v.size();
+        for (int r = 0; r < v.size(); ++r)
+        {
+            switch (v[r][c])
+            {
+                case '#':
+                    floor = v.size() - r - 1;
+                    break;
+                case 'O':
+                    answer += floor--;
+            }
+        }
+    }
+    std::cout << answer << std::endl;
+    return 0;
+}
diff --git a/2023/14/src/part2.cpp b/2023/14/src/part2.cpp
new file mode 100644
index 0000000..7765b3f
--- /dev/null
+++ b/2023/14/src/part2.cpp
@@ -0,0 +1,167 @@
+#include <iostream>
+#include <fstream>
+#include <vector>
+#include <algorithm>
+
+using Dish = std::vector<std::string>;
+using History = std::vector<std::vector<bool>>;
+
+constexpr int CYCLES = 1'000'000'000;
+
+Dish parse(const char* file)
+{
+    Dish v;
+
+    if (std::ifstream input{ file }; input.is_open())
+    {
+        std::string line;
+        while (not std::getline(input,line).eof())
+        {
+            v.push_back(std::move(line));
+        }
+    }
+
+    return v;
+}
+
+std::vector<bool> encode(const Dish& v)
+{
+    auto len = v.size();
+    std::vector<bool> e(len * len, 0);
+    for (int x = 0; x < len; ++x)
+    {
+        for (int y = 0; y < len; ++y)
+        {
+            e[x * len + y] = v[x][y] == 'O';
+        }
+    }
+    return e;
+}
+
+Dish& tilt_north(Dish& v)
+{
+    for (int c = 0; c < v.size(); ++c)
+    {
+        int floor{};
+        for (int r = floor; r < v.size(); ++r)
+        {
+            switch (v[r][c])
+            {
+                case '#':
+                    floor = r + 1;
+                    break;
+                case 'O':
+                    v[r][c] = '.';
+                    v[floor++][c] = 'O';
+            }
+        }
+    }
+    return v;
+}
+
+Dish& tilt_south(Dish& v)
+{
+    for (int c = 0; c < v.size(); ++c)
+    {
+        int floor{ static_cast<int>(v.size() - 1) };
+        for (int r = floor; r >= 0; --r)
+        {
+            switch (v[r][c])
+            {
+                case '#':
+                    floor = r - 1;
+                    break;
+                case 'O':
+                    v[r][c] = '.';
+                    v[floor--][c] = 'O';
+            }
+        }
+    }
+    return v;
+}
+
+Dish& tilt_west(Dish& v)
+{
+    for (int r = 0; r < v.size(); ++r)
+    {
+        int floor{};
+        for (int c = floor; c < v.size(); ++c)
+        {
+            switch (v[r][c])
+            {
+                case '#':
+                    floor = c + 1;
+                    break;
+                case 'O':
+                    v[r][c] = '.';
+                    v[r][floor++] = 'O';
+            }
+        }
+    }
+    return v;
+}
+
+Dish& tilt_east(Dish& v)
+{
+    for (int r = 0; r < v.size(); ++r)
+    {
+        int floor{ static_cast<int>(v.size() - 1) };
+        for (int c = floor; c >= 0; --c)
+        {
+            switch (v[r][c])
+            {
+                case '#':
+                    floor = c - 1;
+                    break;
+                case 'O':
+                    v[r][c] = '.';
+                    v[r][floor--] = 'O';
+            }
+        }
+    }
+    return v;
+}
+
+Dish& cycle(Dish& v)
+{
+    return tilt_east(tilt_south(tilt_west(tilt_north(v))));
+}
+
+int load(const std::vector<bool>& v, int l)
+{
+    int load{};
+    for (int x = 0; x < l; ++x)
+    {
+        for (int y = 0; y < l; ++y)
+        {
+            load += (l - x) * v[x * l + y];
+        }
+    }
+    return load;
+}
+
+int dup(History& hist, Dish dish)
+{
+    auto h = encode(dish);
+    if (auto found = std::find(hist.cbegin(), hist.cend(), h); found != hist.cend())
+    {
+        return hist.cend() - found;
+    }
+    hist.push_back(std::move(h));
+    return 0;
+}
+
+int main(int argc, char* argv[])
+{
+    auto v = parse(argv[1]);
+
+    History history;
+    history.push_back(encode(v));
+
+    int p, np;
+    for (p = 0; p == 0; p = dup(history, cycle(v)));
+    np = history.size() - p;
+
+    std::cout << load(history[np + (CYCLES - np) % p], v.size()) << std::endl;
+    return 0;
+}