aoc 2024, day 20, part 2

1 files changed, 25 insertions, 0 deletions

diff --git a/2024/src/day20.cpp b/2024/src/day20.cpp
index 42a2fba..3e79f33 100644
--- a/2024/src/day20.cpp
+++ b/2024/src/day20.cpp
@@ -100,9 +100,34 @@ part1(const tuple<pos_type, pos_type, set<pos_type>>& data)
         cout << count << endl;
 }
 
+void
+part2(const tuple<pos_type, pos_type, set<pos_type>>& data)
+{
+        auto path = bfs(data);
+
+        long count = 0;
+        for ( const auto& [pos, dist]: path ) {
+                auto [x, y] = pos;
+
+                for ( size_t r = 2; r != 21; ++r ) {
+                        for ( size_t dx = 0; dx != r + 1; ++dx ) {
+                                size_t dy = r - dx;
+
+                                for ( const auto& new_pos: set<pos_type>{ { x + dx, y + dy }, { x - dx, y + dy }, { x + dx, y - dy }, { x - dx, y - dy } } ) {
+                                        if ( path.contains(new_pos) && dist < path.at(new_pos) && path.at(new_pos) - dist >= 100 + long(r) ) {
+                                                ++count;
+                                        }
+                                }
+                        }
+                }
+        }
+        cout << count << endl;
+}
+
 int
 main()
 {
         auto data = read_file("data/day20.txt");
         part1(data);
+        part2(data);
 }