Add 2022 day 18 cpp

2022/README.md

@@ -25,3 +25,4 @@ This folder contains solutions to each of the problems in Advent of Code 2022 in
 | <nobr> [Day 15: Beacon Exclusion Zone](https://adventofcode.com/2022/day/15) </nobr> | <nobr> [Part 1](/2022/cpp/day_15a.cpp) [Part 2](/2022/cpp/day_15b.cpp) </nobr> | </nobr> [Link](/2022/input/day_15_input) </nobr> | </nobr> [Link](/2022/sample_input/day_15_sample_input) </nobr> | </nobr> [Link](/2022/puzzles/day_15_puzzle) </nobr> |
 | <nobr> [Day 16: Proboscidea Volcanium](https://adventofcode.com/2022/day/16) </nobr> | <nobr> [Part 1](/2022/cpp/day_16a.cpp) [Part 2](/2022/cpp/day_16b.cpp) </nobr> | </nobr> [Link](/2022/input/day_16_input) </nobr> | </nobr> [Link](/2022/sample_input/day_16_sample_input) </nobr> | </nobr> [Link](/2022/puzzles/day_16_puzzle) </nobr> |
 | <nobr> [Day 17: Pyroclastic Flow](https://adventofcode.com/2022/day/17) </nobr> | <nobr> [Part 1](/2022/cpp/day_17a.cpp) [Part 2](/2022/cpp/day_17b.cpp) </nobr> | </nobr> [Link](/2022/input/day_17_input) </nobr> | </nobr> [Link](/2022/sample_input/day_17_sample_input) </nobr> | </nobr> [Link](/2022/puzzles/day_17_puzzle) </nobr> |
+| <nobr> [Day 18: Boiling Boulders](https://adventofcode.com/2022/day/18) </nobr> | <nobr> [Part 1](/2022/cpp/day_18a.cpp) [Part 2](/2022/cpp/day_18b.cpp) </nobr> | </nobr> [Link](/2022/input/day_18_input) </nobr> | </nobr> [Link](/2022/sample_input/day_18_sample_input) </nobr> | </nobr> [Link](/2022/puzzles/day_18_puzzle) </nobr> |

2022/cpp/day_17a.cpp

@@ -1,8 +1,8 @@
 #include <array>
-#include <unordered_set>
 #include <fstream>
 #include <iostream>
 #include <string>
+#include <unordered_set>
 #include <vector>
 
 struct Point {
@@ -50,13 +50,6 @@ void add_rock_to_chamber(std::vector<std::array<char, 7>>& chamber, const Rock&
 }
 
 void apply_jet(Rock& rock, const std::string& jets, const int jet_index, const std::vector<std::array<char, 7>>& chamber) {
-  // std::cout << jets << '\n';
-  // for (int i = 0; i < jet_index; i++) {
-  //   std::cout << ' ';
-  // }
-  // std::cout << '^';
-  // std::cout << '\n';
-  // std::cout << j << '\n';
   const auto prev = rock;
   if (const char j = jets[jet_index]; j == '>') {
     for (auto& ele : rock) {
@@ -133,42 +126,20 @@ int main(int argc, char * argv[]) {
   std::array<char, 7> temp;
   std::fill(std::begin(temp), std::end(temp), '#');
   chamber.push_back(temp);
-  // print_chamber(chamber);
-  // exit(0);
-  // std::cout << __LINE__ <<'\n';
   while (rock_count < 2022) {
-    // std::cout << "---------------- Begin -------------------" << '\n';
     auto rock = rocks[rock_count % 5];
     rock_count++;
-    // std::cout << __LINE__ <<'\n';
     move_to_starting_height(rock, highest);
-    // std::cout << __LINE__ <<'\n';
     auto prev = rock;
-    // move(rock);
-    // print(rock);
-
     while (!intersection(chamber, rock)) {
-      // std::cout << __LINE__ <<'\n';
       apply_jet(rock, jets, jet_index, chamber);
-      // std::cout << __LINE__ <<'\n';
-      // print(rock);
-      // std::cout << __LINE__ <<'\n';
       jet_index++;
       if (jet_index == jets.size()) jet_index = 0;
       prev = rock;
       move(rock);
-      // std::cout << __LINE__ <<'\n';
-      // print(rock);
     }
-    // print(prev);
-    // std::cout << __LINE__ <<'\n';
     add_rock_to_chamber(chamber, prev);
-    // std::cout << __LINE__ <<'\n';
-    // print(chamber);
     highest = chamber.size();
-    // std::cout << "---------------- End -------------------" << '\n';
-    // print_chamber(chamber);
-    // if (rock_count == 10) exit(0);
   }
   std::cout << highest - 1 << '\n';
 }

2022/cpp/day_17b.cpp

@@ -10,7 +10,8 @@
 // even when adding in jet index and rock type to the == comparator.
 // 5 rows of the chamber is arbitrary, might be able to make do with less.
 
-// TODO: use bitset and optimize
+// TODO: use bitset instead of array<char>
+// though array<bool> might be faster than bitset
 
 struct Point {
   Point(const std::size_t row, const int col) : row (row), col(col) {}
@@ -78,9 +79,9 @@ void add_rock_to_chamber(
   const Rock& rock
 ) {
   for (const auto& ele : rock) {
+    std::array<char, n_cols_in_chamber> temp;
+    std::fill(std::begin(temp), std::end(temp), '.');
     while(chamber.size() <= ele.row) {
-      std::array<char, n_cols_in_chamber> temp;
-      std::fill(std::begin(temp), std::end(temp), '.');
       chamber.push_back(temp);
     }
   }
@@ -90,6 +91,7 @@ void add_rock_to_chamber(
 }
 
 void apply_jet(Rock& rock, const std::string& jets, const int jet_index, const std::vector<std::array<char, n_cols_in_chamber>>& chamber) {
+  // Debug
   // for (int i = 0; i < jet_index; i++) {
   //   std::cout << ' ';
   // }
@@ -125,7 +127,7 @@ void print(const Rock& rock) {
 }
 
 void print_chamber(const Chamber& chamber) {
-  std::cout << chamber.size() << '\n';
+  std::cout << "Chamber size: " << chamber.size() << '\n';
   for (std::size_t i = chamber.size()-1; i > 0; i--) {
     std::cout << "|";
     for (const auto & ele : chamber[i]) {
@@ -149,7 +151,7 @@ std::tuple<bool, std::size_t, std::size_t> check_if_seen_else_add(
     return {true, it->second, it->first.highest};
   }
   history[memory] = iteration;
-  return {false, -1, -1};
+  return {false, 0, 0};
 }
 
 int main(int argc, char * argv[]) {
@@ -179,14 +181,15 @@ int main(int argc, char * argv[]) {
   int rock_count = 0;
   int jet_index = 0;
   std::vector<std::array<char, n_cols_in_chamber>> chamber;
+  std::unordered_map<Memory, std::size_t, MemoryHash> history;
   std::array<char, n_cols_in_chamber> temp;
   std::fill(std::begin(temp), std::end(temp), '#');
   chamber.push_back(temp);
-  Chamber top_n;
+
+  Chamber top_n; // Mini chamber, top_n rows of chamber
   for (auto& row : top_n) {
     std::fill(std::begin(row), std::end(row), 0);
   }
-  std::unordered_map<Memory, std::size_t, MemoryHash> history;
 
   while (rock_count < 1000000000000) {
     auto rock = rocks[rock_count % 5];

2022/cpp/day_18a.cpp

@@ -0,0 +1,68 @@
+#include <algorithm>
+#include <array>
+#include <fstream>
+#include <iostream>
+#include <string>
+#include <unordered_map>
+#include <vector>
+
+using Point = std::array<int, 3>;
+
+struct PointHash {
+  std::size_t operator () (const Point& p) const {
+    std::size_t ans = 0;
+    for (const auto ele : p) {
+      ans = ans * 10 + ele;
+    }
+    return ans;
+  }
+};
+
+int main(int argc, char * argv[]) {
+  std::string input = "../input/day_18_input";
+  if (argc > 1) {
+    input = argv[1];
+  }
+  std::string line;
+  std::fstream file(input);
+
+  std::unordered_map<Point, int, PointHash> points;
+
+  const auto get_neighbours = [] (const Point& p) {
+    return std::array<Point, 6>{{
+      Point{{p[0]-1, p[1], p[2]}},
+      Point{{p[0]+1, p[1], p[2]}},
+      Point{{p[0], p[1]-1, p[2]}},
+      Point{{p[0], p[1]+1, p[2]}},
+      Point{{p[0], p[1], p[2]-1}},
+      Point{{p[0], p[1], p[2]+1}}
+    }};
+  };
+
+  while(std::getline(file, line)) {
+    std::size_t start = 0;
+    std::size_t end = line.find(',');
+    Point p;
+    int index = 0;
+    while(end != std::string::npos) {
+      p[index] = std::stoi(line.substr(start, end - start));
+      start = end + 1;
+      end = line.find(',', start);
+      index++;
+    }
+    p[index] = std::stoi(line.substr(start, end - start));
+    points[p] = 0;
+    for (const auto& neighbour: get_neighbours(p)) {
+      if (const auto it = points.find(neighbour); it != points.end()) {
+        points[p]++;
+        it->second += 1;
+      }
+    }
+  }
+  int total_sa = points.size() * 6;
+  for (const auto& [point, n_neighbours] : points) {
+    total_sa -= n_neighbours;
+  }
+  std::cout << total_sa << '\n';
+  return 0;
+}