day 3 solution on c++ :3

2020/day_3/toboggan_trajectory.py

@@ -22,7 +22,9 @@ def solve_a():
 
 def solve_b():
     slopes = ((1, 1), (3, 1), (5, 1), (7, 1), (1, 2))
-    return prod([count_trees(slope) for slope in slopes])
+    results = [count_trees(slope) for slope in slopes]
+    print(results)
+    return prod(results)
 
 
 print(solve_a())

2020/day_3/toboggan_trayectory.cc

@@ -0,0 +1,57 @@
+#include <fstream>
+#include <iostream>
+#include <string>
+#include <vector>
+
+std::vector<std::string> read_input_file() {
+  std::ifstream file("input");
+  std::vector<std::string> data;
+  std::string line;
+
+  while(std::getline(file, line)) 
+    data.push_back(line);
+
+  return data;
+}
+
+struct slope{ int x; int y; };
+
+int count_trees(std::vector<std::string> map, const slope &s){
+  int trees = 0;
+
+  int x = s.x;
+  int y = s.y;
+  int w = map[0].size();
+  int h = map.size();
+
+  while(y < h) {
+    if(map[y][x%w] == '#') trees++;
+
+    x += s.x;
+    y += s.y;
+  }
+
+  return trees;
+}
+
+int solve_a(std::vector<std::string> map) {
+  return count_trees(map, {3, 1});
+}
+
+long solve_b(std::vector<std::string> map) {
+  std::vector<slope> slopes {{1, 1}, {3, 1}, {5, 1}, {7, 1}, {1, 2}};
+
+  long result = 1;
+  for(auto& slope: slopes) result *= count_trees(map, slope);
+  return result;
+}
+
+
+int main() {
+  auto data = read_input_file();
+
+  std::cout << solve_a(data) << std::endl;
+  std::cout << solve_b(data) << std::endl;
+
+  return 0;
+}