Implement day 10 part 1.

2019/src/day10.cpp

@@ -1,8 +1,55 @@
 #include <iostream>
+#include <numeric>
+#include <unordered_set>
 #include "days.hpp"
+#include "point.hpp"
+
+namespace {
+    typedef aoc2019::Point<int, 2> point_t;
+
+    std::vector<point_t> read_points(std::istream& input) {
+        std::vector<point_t> result;
+
+        int y = 0;
+
+        for (std::string buffer; std::getline(input, buffer); ++y) {
+            std::size_t x = 0;
+
+            while ((x = buffer.find('#', x)) != std::string::npos) {
+                result.push_back({(int) x, y});
+                x += 1;
+            }
+        }
+
+        return result;
+    }
+
+    point_t simplify(point_t x) {
+        auto gcd = std::abs(std::gcd(x[0], x[1]));
+        if (gcd > 1) {
+            return { x[0] / gcd, x[1] / gcd };
+        }
+
+        return x;
+    }
+}
 
 void aoc2019::day10_part1(std::istream &input, std::ostream &output) {
-	output << "Not implemented\n";
+    const auto points = read_points(input);
+    std::size_t best = 0;
+
+    for (auto point : points) {
+        std::unordered_set<point_t> visible;
+
+        for (auto asteroid : points) {
+            if (asteroid == point) continue;
+            visible.insert(simplify(asteroid - point));
+        }
+
+        best = std::max(visible.size(), best);
+    }
+
+	output << best << std::endl;
 }
 
 void aoc2019::day10_part2(std::istream &input, std::ostream &output) {