day 12

12/.gitignore

@@ -0,0 +1 @@
+day12

12/README.md

@@ -0,0 +1,9 @@
+# [Day 12](https://adventofcode.com/2022/day/12) 
+:gift::gift::gift::gift::gift::gift::gift::gift::gift::gift::gift::gift:
+
+Today's language: **C++**
+
+```shell
+g++ -std=c++20 day12.cpp -o day12
+./day12
+```

12/day12.cpp

@@ -0,0 +1,164 @@
+#include <fstream> 
+#include <sstream>
+#include <iostream>
+#include <string>
+#include <cassert>
+#include <unordered_set>
+#include <gz-util/container/queue.hpp>
+
+
+constexpr char UP = (1 << 1);
+constexpr char DOWN = (1 << 2);
+constexpr char LEFT = (1 << 3);
+constexpr char RIGHT = (1 << 4);
+
+using ssize = std::string::size_type;
+
+struct XY {
+    ssize x;
+    ssize y;
+    bool operator==(const XY& other) const { return this->x == other.x && this->y == other.y; };
+    struct Hash {
+        size_t operator()(const XY& xy) const {
+            return (std::hash<ssize>()(xy.x) << 1) ^ (std::hash<ssize>()(xy.y));
+        }
+    };
+};
+
+class String2D {
+    public:
+        String2D(ssize w, std::string::size_type h, char c) : s((w + 1) * h, c), width(w), height(h) {
+            for (ssize i = width; i < s.size(); i += width + 1) {
+                s.at(i) = '\n';
+            }
+        }
+        String2D(std::string&& str) : s(std::move(str)) {
+            width = s.find('\n');
+            height = s.size() / (width + 1);
+        }
+        const char& at(ssize x, std::string::size_type y) const {
+            assert(x < width);
+            assert(y < height);
+            return s.at(x + y * (width + 1));
+        }
+        char& at(ssize x, std::string::size_type y) {
+            assert(x < width);
+            assert(y < height);
+            return s.at(x + y * (width + 1));
+        }
+        void set(ssize x, std::string::size_type y, char c) {
+            assert(x < width);
+            assert(y < height);
+            s.at(x + y * (width + 1)) = c;
+        }
+        XY find(char c) {
+            ssize i = s.find(c);
+            if (i != std::string::npos) { return indexToPos(i); }
+            return XY{std::string::npos, std::string::npos};
+        }
+        XY indexToPos(ssize i) { return XY{.x = i % (width + 1), .y = i / (width + 1) }; }
+        inline const ssize& getWidth() const { return width; }
+        inline const ssize& getHeight() const { return height; }
+        const std::string& getString() const { return s; }
+    private:
+        std::string s;
+        ssize width, height;
+};
+
+bool isReachable(char c) {
+    return c <= 1;
+}
+
+String2D createNodes(const String2D& hill) {
+    String2D dirs(hill.getWidth(), hill.getHeight(), 0);
+    for (size_t x = 0; x < hill.getWidth(); x++) {
+        for (size_t y = 0; y < hill.getHeight(); y++) {
+            char c = hill.at(x, y);
+            if (x > 0) {
+                if (isReachable(hill.at(x - 1, y) - c)) { dirs.at(x, y) |= LEFT; }
+            }
+            if (x < hill.getWidth() - 1) {
+                if (isReachable(hill.at(x + 1, y) - c)) { dirs.at(x, y) |= RIGHT; }
+            }
+            if (y > 0) {
+                if (isReachable(hill.at(x, y - 1) - c)) { dirs.at(x, y) |= UP; }
+            }
+            if (y < hill.getHeight() - 1) {
+                if (isReachable(hill.at(x, y + 1) - c)) { dirs.at(x, y) |= DOWN; }
+            }
+        }
+    }
+    return dirs;
+}
+
+ssize shortestPath(const String2D& nodes, XY start, XY end) {
+    gz::Queue<XY> waitlists[2];
+    unsigned currentWaitlist = 0;
+    unsigned otherWaitlist = 1;
+    std::unordered_set<XY, XY::Hash> processed;
+    ssize length = 0;
+    auto queue = [&processed](gz::Queue<XY>& q, XY xy) {
+        if (!processed.contains(xy)) {
+            processed.insert(xy);
+            q.push_back(xy);
+        }
+    };
+    queue(waitlists[currentWaitlist], start);
+    while (waitlists[0].hasElement() || waitlists[1].hasElement()) {
+        while (waitlists[currentWaitlist].hasElement()) {
+            XY& pos = waitlists[currentWaitlist].getRef();
+            if (pos == end) { goto done; }
+            char c = nodes.at(pos.x, pos.y);
+            if (c & LEFT) { queue(waitlists[otherWaitlist], XY{pos.x - 1, pos.y}); }
+            if (c & RIGHT) { queue(waitlists[otherWaitlist], XY{pos.x + 1, pos.y}); }
+            if (c & UP) { queue(waitlists[otherWaitlist], XY{pos.x, pos.y - 1}); }
+            if (c & DOWN) { queue(waitlists[otherWaitlist], XY{pos.x, pos.y + 1}); }
+        }
+        otherWaitlist = currentWaitlist;
+        currentWaitlist = ++currentWaitlist % 2;
+        length++;
+    }
+    std::cerr << "Could not find path\n";
+    return std::string::npos;
+done:
+    return length;
+}
+
+
+int main(int argc, const char** argv) {
+    const char* filename;
+    if (argc != 2) { filename = "hill.txt"; }
+    else { filename = argv[1]; }
+
+    std::ifstream file(filename);
+    if (!file.is_open()) {
+        std::cout << "Could not open file\n";
+        return 1;
+    }
+    std::ostringstream ss;
+    ss << file.rdbuf();
+    file.close();
+    String2D hill2D(ss.str());
+    XY start = hill2D.find('S');
+    XY end = hill2D.find('E');
+    hill2D.at(start.x, start.y) = 'a';
+    hill2D.at(end.x, end.y) = 'z';
+    /* printf("Start: (%lu, %lu), End: (%lu, %lu)\n", start.x, start.y, end.x, end.y); */
+    auto nodes = createNodes(hill2D);
+    ssize length = shortestPath(nodes, start, end);
+    std::cout << "Shortest path has length: " << length << "\n";
+
+    // Task 2
+    ssize minLength = std::string::npos;
+    ssize startAt = 0;
+    ssize aIndex = hill2D.getString().find('a', startAt);
+    while (aIndex != std::string::npos) {
+        XY pos = hill2D.indexToPos(aIndex);
+        ssize length_ = shortestPath(nodes, hill2D.indexToPos(aIndex), end);
+        /* printf("Path from (%lu, %lu) to end has length: %lu\n", pos.x, pos.y, length_); */
+        if (length_ < minLength) { minLength = length_; }
+        startAt = aIndex + 1;
+        aIndex = hill2D.getString().find('a', startAt);
+    }
+    printf("Shortest path from any a has length %lu\n", minLength);
+}

12/hill.txt

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+abccccaaaaaaacccaaaaaaaccccccccccccccccccccccccccccccccccaaaa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README.md

@@ -23,7 +23,7 @@ Also, check out the repositories of my friends who do stuff in go, Visual Basic,
 - **Assembly, x86-64**: day 4
 - **Bash**: day 1, 7
 - **C**: day 3, 4
-- **C++**: day 2, 8, 14
+- **C++**: day 2, 8, 12, 14
 - **HolyC:** day 13
 - **Java**: day 10
 - **Javascript**: day 6