Add 2022 day 09 cpp

2022/README.md

@@ -3,6 +3,7 @@
 This folder contains solutions to each of the problems in Advent of Code 2022 in C++.
 
 #### Note ####
+- The sample puzzles for some days (eg 9) multiple sample inputs. Edit the file before using it.
 
 |Puzzle|C++ Solutions|Input|Sample Input|Puzzle page with solutions|
 |:---:|:---:|:---:|:---:|:---:|
@@ -14,3 +15,4 @@ This folder contains solutions to each of the problems in Advent of Code 2022 in
 | <nobr> [Day 6: Tuning Trouble](https://adventofcode.com/2022/day/6) </nobr> | <nobr> [Part 1](/2022/cpp/day_06a.cpp) [Part 2](/2022/cpp/day_06b.cpp) </nobr> | </nobr> [Link](/2022/input/day_06_input) </nobr> | </nobr> [Link](/2022/sample_input/day_06_sample_input) </nobr> | </nobr> [Link](/2022/puzzles/day_06_puzzle) </nobr> |
 | <nobr> [Day 7: No Space Left On Device](https://adventofcode.com/2022/day/7) </nobr> | <nobr> [Part 1](/2022/cpp/day_07a.cpp) [Part 2](/2022/cpp/day_07b.cpp) </nobr> | </nobr> [Link](/2022/input/day_07_input) </nobr> | </nobr> [Link](/2022/sample_input/day_07_sample_input) </nobr> | </nobr> [Link](/2022/puzzles/day_07_puzzle) </nobr> |
 | <nobr> [Day 8: Treetop Tree House](https://adventofcode.com/2022/day/8) </nobr> | <nobr> [Part 1](/2022/cpp/day_08a.cpp) [Part 2](/2022/cpp/day_08b.cpp) </nobr> | </nobr> [Link](/2022/input/day_08_input) </nobr> | </nobr> [Link](/2022/sample_input/day_08_sample_input) </nobr> | </nobr> [Link](/2022/puzzles/day_08_puzzle) </nobr> |
+| <nobr> [Day 9: Rope Bridge](https://adventofcode.com/2022/day/9) </nobr> | <nobr> [Part 1](/2022/cpp/day_09a.cpp) [Part 2](/2022/cpp/day_09b.cpp) </nobr> | </nobr> [Link](/2022/input/day_09_input) </nobr> | </nobr> [Link](/2022/sample_input/day_09_sample_input) </nobr> | </nobr> [Link](/2022/puzzles/day_09_puzzle) </nobr> |

2022/cpp/day_09a.cpp

@@ -0,0 +1,50 @@
+#include <array>
+#include <unordered_set>
+#include <fstream>
+#include <iostream>
+#include <string>
+
+// TODO: Improve hash function
+
+int main(int argc, char * argv[]) {
+  std::string input = "../input/day_09_input";
+  if (argc > 1) {
+    input = argv[1];
+  }
+
+  std::string line;
+  std::fstream file(input);
+
+  std::array<int, 2> point_H = {0, 0};
+  std::array<int, 2> point_T = {0, 0};
+  std::unordered_set<int> s;
+  while(std::getline(file, line)) {
+    for (int i = 0; i < std::stoi(line.substr(2, line.size() - 2)); i++) {
+      if (line[0] == 'U') {
+        point_H[0] += 1;
+      } else if (line[0] == 'D') {
+        point_H[0] -= 1;
+      } else if (line[0] == 'R') {
+        point_H[1] += 1;
+      } else {
+        point_H[1] -= 1;
+      }
+
+      const auto delta = std::array<int,2>{point_H[0] - point_T[0], point_H[1] - point_T[1]};
+      if (std::abs(delta[0]) == 2 && std::abs(delta[1]) == 0) {
+        point_T[0] += delta[0]/2;
+      } else if (std::abs(delta[0]) == 2 && std::abs(delta[1]) == 1) {
+        point_T[0] += delta[0]/2;
+        point_T[1] += delta[1];
+      } else if (std::abs(delta[0]) == 0 && std::abs(delta[1]) == 2) {
+        point_T[1] += delta[1]/2;
+      } else if (std::abs(delta[0]) == 1 && std::abs(delta[1]) == 2) {
+        point_T[0] += delta[0];
+        point_T[1] += delta[1]/2;
+      }
+      s.insert(point_T[0] * 100000 + point_T[1]);
+    }
+  }
+  std::cout << s.size() << '\n';
+  return 0;
+}

2022/cpp/day_09b.cpp

@@ -0,0 +1,64 @@
+#include <array>
+#include <fstream>
+#include <iostream>
+#include <string>
+#include <unordered_set>
+
+// TODO: Improve hash function
+
+void update_pair(const int k1, const int k2, std::array<std::array<int,2>, 10>& knots) {
+  const auto delta = std::array<int,2>{knots[k1][0] - knots[k2][0], knots[k1][1] - knots[k2][1]};
+  if (std::abs(delta[0]) == 2 && std::abs(delta[1]) == 0) {
+    knots[k2][0] += delta[0]/2;
+  } else if (std::abs(delta[0]) == 2 && std::abs(delta[1]) == 1) {
+    knots[k2][0] += delta[0]/2;
+    knots[k2][1] += delta[1];
+  } else if (std::abs(delta[0]) == 0 && std::abs(delta[1]) == 2) {
+    knots[k2][1] += delta[1]/2;
+  } else if (std::abs(delta[0]) == 1 && std::abs(delta[1]) == 2) {
+    knots[k2][0] += delta[0];
+    knots[k2][1] += delta[1]/2;
+  } else if (std::abs(delta[0]) == 2 && std::abs(delta[1]) == 2) {
+    knots[k2][0] += delta[0]/2;
+    knots[k2][1] += delta[1]/2;
+  }
+}
+
+int main(int argc, char * argv[]) {
+  std::string input = "../input/day_09_input";
+  if (argc > 1) {
+    input = argv[1];
+  }
+
+  std::string line;
+  std::fstream file(input);
+
+  std::array<std::array<int, 2>, 10> knots;
+  for (auto& row : knots) {
+    for (auto& ele : row) {
+      ele = 0;
+    }
+  }
+
+  std::unordered_set<int> s;
+  while(std::getline(file, line)) {
+    for (int i = 0; i < std::stoi(line.substr(2, line.size() - 2)); i++) {
+      if (line[0] == 'U') {
+        knots[0][0] += 1;
+      } else if (line[0] == 'D') {
+        knots[0][0] -= 1;
+      } else if (line[0] == 'R') {
+        knots[0][1] += 1;
+      } else {
+        knots[0][1] -= 1;
+      }
+      for (int i = 0; i < knots.size() - 1; i++) {
+        update_pair(i, i+1, knots);
+      }
+      s.insert(knots[9][0] * 100000 + knots[9][1]);
+    }
+  }
+
+  std::cout << s.size() << '\n';
+  return 0;
+}

2022/sample_input/day_09_sample_input

@@ -0,0 +1,17 @@
+R 4
+U 4
+L 3
+D 1
+R 4
+D 1
+L 5
+R 2
+
+R 5
+U 8
+L 8
+D 3
+R 17
+D 10
+L 25
+U 20

README.md

@@ -6,7 +6,7 @@ This repository contains solutions to the Advent of Code puzzles.
 
 | Year | C++ | Python | Link to folders | Link to README.md |
 |:----:|:----:|:----:|:----:|:----:|
-|2022  |1-8 | - | [Link](/2022/) |[Link](/2022/README.md) |
+|2022  |1-9 | - | [Link](/2022/) |[Link](/2022/README.md) |
 |2021  |1-25 | - | [Link](/2021/) |[Link](/2021/README.md) |
 |2020  |1-25 |1-25 | [Link](/2020/) |[Link](/2020/README.md) |
 |2019  |1-25 |1-7  | [Link](/2019/) |[Link](/2019/README.md) |