feat: day10 (#14)

Author: martabal

.gitignore

@@ -4,4 +4,4 @@
 /build
 /perf
 Makefile
-.reponse
+.response

Cargo.lock

@@ -10,6 +10,7 @@ members = [
     "crates/day07",
     "crates/day08",
     "crates/day09",
+    "crates/day10",
     "crates/helpers",
 ]
 

Cargo.toml

@@ -211,8 +211,10 @@ int main() {
   try {
     string message = readFile("crates/day06/input.txt");
     Lab grid(message);
+
     // --- Part One ---
     cout << "Part One solution: " << grid.findPath() << endl;
+
     // --- Part Two ---
     cout << "Part Two solution: " << grid.findIfStuck() << endl;
   } catch (const exception &e) {

cpp/day06.cc

@@ -154,7 +154,7 @@ int main() {
     std::cout << "Part Two solution: " << checker.count_antennas(true)
               << std::endl;
   } catch (const std::exception &e) {
-    std::cerr << e.what() << std::endl;
+    std::cerr << "Error: " << e.what() << "\n";
   }
 
   return 0;

cpp/day08.cc

@@ -176,8 +176,8 @@ int main() {
     std::cout << "Part Two solution: "
               << FileSystem::calculateChecksum(checker.getFiles()) << "\n";
 
-  } catch (const std::exception &ex) {
-    std::cerr << "Error: " << ex.what() << "\n";
+  } catch (const std::exception &e) {
+    std::cerr << "Error: " << e.what() << "\n";
     return 1;
   }
   return 0;

cpp/day09.cc

@@ -0,0 +1,135 @@
+#include "helpers.h"
+#include <fstream>
+#include <iostream>
+#include <sstream>
+#include <string>
+#include <unordered_map>
+#include <unordered_set>
+#include <vector>
+
+const std::vector<std::pair<int, int>> DIRECTIONS = {
+    {0, 1},  // Right
+    {1, 0},  // Down
+    {0, -1}, // Left
+    {-1, 0}  // Up
+};
+
+class TrailHeads {
+public:
+  TrailHeads(const std::string &content) {
+    std::istringstream stream(content);
+    std::string line;
+    int row = 0;
+
+    while (std::getline(stream, line)) {
+      for (int col = 0; col < line.size(); ++col) {
+        char ch = line[col];
+        if (isdigit(ch)) {
+          int height = ch - '0';
+          auto coords = std::make_pair(row, col);
+          if (height == 0) {
+            trailheads.push_back(coords);
+          }
+          grid[coords] = height;
+        }
+      }
+      row++;
+    }
+  }
+
+  size_t count_trailheads() const {
+    size_t total = 0;
+    for (const auto &head : trailheads) {
+      total += count_trail_unique(head, 0).size();
+    }
+    return total;
+  }
+
+  size_t count_distinct_trailheads() const {
+    size_t total = 0;
+    for (const auto &head : trailheads) {
+      total += count_trail_all(head, 0);
+    }
+    return total;
+  }
+
+private:
+  struct pair_hash {
+    template <class T1, class T2>
+    std::size_t operator()(const std::pair<T1, T2> &pair) const {
+      auto hash1 = std::hash<T1>{}(pair.first);
+      auto hash2 = std::hash<T2>{}(pair.second);
+      return hash1 ^ hash2;
+    }
+  };
+  std::vector<std::pair<int, int>> trailheads;
+  std::unordered_map<std::pair<int, int>, int, pair_hash> grid;
+
+  std::unordered_set<std::pair<int, int>, pair_hash>
+  count_trail_unique(const std::pair<int, int> &position, int height) const {
+    std::unordered_set<std::pair<int, int>, pair_hash> res;
+
+    for (const auto &[row_dir, col_dir] : DIRECTIONS) {
+      auto new_dir =
+          std::make_pair(position.first + row_dir, position.second + col_dir);
+      auto it = grid.find(new_dir);
+      if (it != grid.end()) {
+        int new_pos = it->second;
+        if (height + 1 != new_pos) {
+          continue;
+        }
+
+        if (new_pos == 9) {
+          res.insert(new_dir);
+        } else {
+          auto unique_trails = count_trail_unique(new_dir, new_pos);
+          res.insert(unique_trails.begin(), unique_trails.end());
+        }
+      }
+    }
+    return res;
+  }
+
+  size_t count_trail_all(const std::pair<int, int> &position,
+                         int height) const {
+    size_t res = 0;
+    for (const auto &[row_dir, col_dir] : DIRECTIONS) {
+      auto new_dir =
+          std::make_pair(position.first + row_dir, position.second + col_dir);
+      auto it = grid.find(new_dir);
+      if (it != grid.end()) {
+        int new_pos = it->second;
+        if (height + 1 != new_pos) {
+          continue;
+        }
+
+        if (new_pos == 9) {
+          res++;
+        } else {
+          res += count_trail_all(new_dir, new_pos);
+        }
+      }
+    }
+    return res;
+  }
+};
+
+int main() {
+  try {
+    std::string message = readFile("crates/day10/input.txt");
+    TrailHeads checker(message);
+
+    // --- Part One ---
+    std::cout << "Part One solution: " << checker.count_trailheads()
+              << std::endl;
+
+    // --- Part Two ---
+    std::cout << "Part Two solution: " << checker.count_distinct_trailheads()
+              << std::endl;
+
+  } catch (const std::exception &e) {
+    std::cerr << "Error: " << e.what() << std::endl;
+  }
+
+  return 0;
+}

cpp/day10.cc

@@ -0,0 +1,10 @@
+[package]
+name = "day10"
+version = "0.1.0"
+edition = "2021"
+
+[lints]
+workspace = true
+
+[dependencies]
+helpers = { path = "../helpers"}

crates/day01/.response

@@ -0,0 +1,8 @@
+89010123
+78121874
+87430965
+96549874
+45678903
+32019012
+01329801
+10456732

crates/day02/.response

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