diff options
| -rw-r--r-- | src/day06.zig | 28 |
1 files changed, 20 insertions, 8 deletions
diff --git a/src/day06.zig b/src/day06.zig index bbea665..9b7b8b5 100644 --- a/src/day06.zig +++ b/src/day06.zig @@ -27,15 +27,29 @@ pub fn solve(part: []u8, buffer: []u8, allocator: std.mem.Allocator) !void { } } -fn locations(grid: *std.ArrayList([]u8), startx: i32, starty: i32, allocator: std.mem.Allocator) !std.AutoHashMap(std.meta.Tuple(&.{ i32, i32 }), void) { +fn locations(grid: *std.ArrayList([]u8), startx: i32, starty: i32, allocator: std.mem.Allocator) !std.AutoHashMap(std.meta.Tuple(&.{ i32, i32, i32, i32 }), void) { var dirx: i32 = 0; var diry: i32 = -1; var x = startx; var y = starty; - var unique = std.AutoHashMap(std.meta.Tuple(&.{ i32, i32 }), void).init(allocator); + + var history = try allocator.alloc(bool, grid.items.len * grid.items[0].len * 4); + defer allocator.free(history); + + for (history) |*elem| { + elem.* = false; + } + + var unique = std.AutoHashMap(std.meta.Tuple(&.{ i32, i32, i32, i32 }), void).init(allocator); errdefer unique.deinit(); + const width: i32 = @intCast(grid.items[0].len); while (y >= 0 and y < grid.items.len and x >= 0 and x < grid.items[@intCast(y)].len) { + if (!history[@intCast(y * width + x)] and grid.items[@intCast(y)][@intCast(x)] != '#') { + try unique.put(.{ x, y, dirx, diry }, {}); + history[@intCast(y * width + x)] = true; + } + if (grid.items[@intCast(y)][@intCast(x)] == '#') { x -= dirx; y -= diry; @@ -44,8 +58,6 @@ fn locations(grid: *std.ArrayList([]u8), startx: i32, starty: i32, allocator: st diry = temp; } - try unique.put(.{ x, y }, {}); - x += dirx; y += diry; } @@ -85,10 +97,10 @@ fn part2(grid: *std.ArrayList([]u8), startx: i32, starty: i32, allocator: std.me while (iterator.next()) |location| { grid.items[@intCast(location[1])][@intCast(location[0])] = '#'; - var dirx: i32 = 0; - var diry: i32 = -1; - var x = startx; - var y = starty; + var dirx: i32 = location[2]; + var diry: i32 = location[3]; + var x = location[0]; + var y = location[1]; for (history) |*elem| { elem.* = false; |