diff --git a/IDEAS.md b/IDEAS.md
new file mode 100644
index 0000000..2a9197b
--- /dev/null
+++ b/IDEAS.md
@@ -0,0 +1,35 @@
+### 2015/06:
+
+There are very raw implementation with too much iterations. But what if we
+can build search tree for rectangles, and just go through the whole grid the
+only once, and then apply changes per point from all rectanges at once?
+Would it be faster? Or building the search tree will be much complicated than
+performance gains here?
+
+```zig
+  fn part_one() u32 {
+    var count: u32 = 0;
+
+    for (0..grid_size) |x| {
+      for (0..grid_size) |y| {
+        const it = findRectsAt(x, y);
+
+        var state = false;
+
+        while (it.next()) |action| {
+          switch (action) {
+            .on => state = true,
+            .off => state = false,
+            .toggle => state = !state;
+          }
+        }
+
+        if (state) {
+          count += 1
+        }
+      }
+    }
+
+    return count;
+  }
+```
diff --git a/Makefile b/Makefile
index b38ea8d..3da8832 100644
--- a/Makefile
+++ b/Makefile
@@ -1,6 +1,6 @@
 YEAR=2015
 DAY=6
-PART=1
+PART=2
 
 .PHONY: build-native build-web build dev-native dev-web
 
diff --git a/native/solutions/2015/05/part_2.zig b/native/solutions/2015/05/part_2.zig
index 0ae2b83..bf41c89 100644
--- a/native/solutions/2015/05/part_2.zig
+++ b/native/solutions/2015/05/part_2.zig
@@ -6,6 +6,7 @@ const AnyReader = std.io.AnyReader;
 const LineParser = tools.LineParser;
 
 const Pairs = std.hash_map.AutoHashMap([2]u8, usize);
+
 const Overlap = struct {
     byte: u8,
     index: usize,
diff --git a/native/solutions/2015/06/common.zig b/native/solutions/2015/06/common.zig
new file mode 100644
index 0000000..9a8316e
--- /dev/null
+++ b/native/solutions/2015/06/common.zig
@@ -0,0 +1,90 @@
+const std = @import("std");
+const tools = @import("tools");
+
+const Allocator = std.mem.Allocator;
+const AnyReader = std.io.AnyReader;
+const LineParser = tools.LineParser;
+
+pub const Action = enum { on, off, toggle };
+
+pub const Command = struct {
+    action: Action,
+
+    from_x: usize,
+    from_y: usize,
+
+    to_x: usize,
+    to_y: usize,
+};
+
+const Iterator = std.mem.SplitIterator(u8, .any);
+
+fn parseAction(it: *Iterator) !Action {
+    const prelude = it.first();
+
+    if (std.mem.eql(u8, prelude, "toggle")) {
+        return .toggle;
+    }
+
+    if (!std.mem.eql(u8, prelude, "turn")) {
+        return error.InvalidInput;
+    }
+
+    const token = it.next() orelse "";
+
+    if (std.mem.eql(u8, token, "on")) {
+        return .on;
+    }
+
+    if (std.mem.eql(u8, token, "off")) {
+        return .off;
+    }
+
+    return error.InvalidInput;
+}
+
+fn checkThrough(it: *Iterator) !void {
+    const token = it.next() orelse "";
+
+    if (!std.mem.eql(u8, token, "through")) {
+        return error.InvalidInput;
+    }
+}
+
+fn parseValue(it: *Iterator) !usize {
+    const token = it.next() orelse "";
+
+    if (token.len > 3) {
+        return error.InvalidInput;
+    }
+
+    return std.fmt.parseInt(usize, token, 10) catch {
+        return error.InvalidInput;
+    };
+}
+
+fn parse(line: []const u8, _: Allocator) !Command {
+    var it = std.mem.splitAny(u8, line, " ,");
+
+    const action = try parseAction(&it);
+
+    const from_x = try parseValue(&it);
+    const from_y = try parseValue(&it);
+
+    try checkThrough(&it);
+
+    const to_x = try parseValue(&it);
+    const to_y = try parseValue(&it);
+
+    return .{
+        .action = action,
+
+        .from_x = from_x,
+        .from_y = from_y,
+
+        .to_x = to_x,
+        .to_y = to_y,
+    };
+}
+
+pub const Parser = LineParser(Command, parse);
diff --git a/native/solutions/2015/06/input.fixture b/native/solutions/2015/06/input.fixture
new file mode 100644
index 0000000..d6cfb3a
--- /dev/null
+++ b/native/solutions/2015/06/input.fixture
@@ -0,0 +1,300 @@
+toggle 461,550 through 564,900
+turn off 370,39 through 425,839
+turn off 464,858 through 833,915
+turn off 812,389 through 865,874
+turn on 599,989 through 806,993
+turn on 376,415 through 768,548
+turn on 606,361 through 892,600
+turn off 448,208 through 645,684
+toggle 50,472 through 452,788
+toggle 205,417 through 703,826
+toggle 533,331 through 906,873
+toggle 857,493 through 989,970
+turn off 631,950 through 894,975
+turn off 387,19 through 720,700
+turn off 511,843 through 581,945
+toggle 514,557 through 662,883
+turn off 269,809 through 876,847
+turn off 149,517 through 716,777
+turn off 994,939 through 998,988
+toggle 467,662 through 555,957
+turn on 952,417 through 954,845
+turn on 565,226 through 944,880
+turn on 214,319 through 805,722
+toggle 532,276 through 636,847
+toggle 619,80 through 689,507
+turn on 390,706 through 884,722
+toggle 17,634 through 537,766
+toggle 706,440 through 834,441
+toggle 318,207 through 499,530
+toggle 698,185 through 830,343
+toggle 566,679 through 744,716
+toggle 347,482 through 959,482
+toggle 39,799 through 981,872
+turn on 583,543 through 846,710
+turn off 367,664 through 595,872
+turn on 805,439 through 964,995
+toggle 209,584 through 513,802
+turn off 106,497 through 266,770
+turn on 975,2 through 984,623
+turn off 316,684 through 369,876
+turn off 30,309 through 259,554
+turn off 399,680 through 861,942
+toggle 227,740 through 850,829
+turn on 386,603 through 552,879
+turn off 703,795 through 791,963
+turn off 573,803 through 996,878
+turn off 993,939 through 997,951
+turn on 809,221 through 869,723
+turn off 38,720 through 682,751
+turn off 318,732 through 720,976
+toggle 88,459 through 392,654
+turn off 865,654 through 911,956
+toggle 264,284 through 857,956
+turn off 281,776 through 610,797
+toggle 492,660 through 647,910
+turn off 879,703 through 925,981
+turn off 772,414 through 974,518
+turn on 694,41 through 755,96
+turn on 452,406 through 885,881
+turn off 107,905 through 497,910
+turn off 647,222 through 910,532
+turn on 679,40 through 845,358
+turn off 144,205 through 556,362
+turn on 871,804 through 962,878
+turn on 545,676 through 545,929
+turn off 316,716 through 413,941
+toggle 488,826 through 755,971
+toggle 957,832 through 976,992
+toggle 857,770 through 905,964
+toggle 319,198 through 787,673
+turn on 832,813 through 863,844
+turn on 818,296 through 818,681
+turn on 71,699 through 91,960
+turn off 838,578 through 967,928
+toggle 440,856 through 507,942
+toggle 121,970 through 151,974
+toggle 391,192 through 659,751
+turn on 78,210 through 681,419
+turn on 324,591 through 593,939
+toggle 159,366 through 249,760
+turn off 617,167 through 954,601
+toggle 484,607 through 733,657
+turn on 587,96 through 888,819
+turn off 680,984 through 941,991
+turn on 800,512 through 968,691
+turn off 123,588 through 853,603
+turn on 1,862 through 507,912
+turn on 699,839 through 973,878
+turn off 848,89 through 887,893
+toggle 344,353 through 462,403
+turn on 780,731 through 841,760
+toggle 693,973 through 847,984
+toggle 989,936 through 996,958
+toggle 168,475 through 206,963
+turn on 742,683 through 769,845
+toggle 768,116 through 987,396
+turn on 190,364 through 617,526
+turn off 470,266 through 530,839
+toggle 122,497 through 969,645
+turn off 492,432 through 827,790
+turn on 505,636 through 957,820
+turn on 295,476 through 698,958
+toggle 63,298 through 202,396
+turn on 157,315 through 412,939
+turn off 69,789 through 134,837
+turn off 678,335 through 896,541
+toggle 140,516 through 842,668
+turn off 697,585 through 712,668
+toggle 507,832 through 578,949
+turn on 678,279 through 886,621
+toggle 449,744 through 826,910
+turn off 835,354 through 921,741
+toggle 924,878 through 985,952
+turn on 666,503 through 922,905
+turn on 947,453 through 961,587
+toggle 525,190 through 795,654
+turn off 62,320 through 896,362
+turn on 21,458 through 972,536
+turn on 446,429 through 821,970
+toggle 376,423 through 805,455
+toggle 494,896 through 715,937
+turn on 583,270 through 667,482
+turn off 183,468 through 280,548
+toggle 623,289 through 750,524
+turn on 836,706 through 967,768
+turn on 419,569 through 912,908
+turn on 428,260 through 660,433
+turn off 683,627 through 916,816
+turn on 447,973 through 866,980
+turn on 688,607 through 938,990
+turn on 245,187 through 597,405
+turn off 558,843 through 841,942
+turn off 325,666 through 713,834
+toggle 672,606 through 814,935
+turn off 161,812 through 490,954
+turn on 950,362 through 985,898
+turn on 143,22 through 205,821
+turn on 89,762 through 607,790
+toggle 234,245 through 827,303
+turn on 65,599 through 764,997
+turn on 232,466 through 965,695
+turn on 739,122 through 975,590
+turn off 206,112 through 940,558
+toggle 690,365 through 988,552
+turn on 907,438 through 977,691
+turn off 838,809 through 944,869
+turn on 222,12 through 541,832
+toggle 337,66 through 669,812
+turn on 732,821 through 897,912
+toggle 182,862 through 638,996
+turn on 955,808 through 983,847
+toggle 346,227 through 841,696
+turn on 983,270 through 989,756
+turn off 874,849 through 876,905
+turn off 7,760 through 678,795
+toggle 973,977 through 995,983
+turn off 911,961 through 914,976
+turn on 913,557 through 952,722
+turn off 607,933 through 939,999
+turn on 226,604 through 517,622
+turn off 3,564 through 344,842
+toggle 340,578 through 428,610
+turn on 248,916 through 687,925
+toggle 650,185 through 955,965
+toggle 831,359 through 933,536
+turn off 544,614 through 896,953
+toggle 648,939 through 975,997
+turn on 464,269 through 710,521
+turn off 643,149 through 791,320
+turn off 875,549 through 972,643
+turn off 953,969 through 971,972
+turn off 236,474 through 772,591
+toggle 313,212 through 489,723
+toggle 896,829 through 897,837
+toggle 544,449 through 995,905
+turn off 278,645 through 977,876
+turn off 887,947 through 946,977
+turn on 342,861 through 725,935
+turn on 636,316 through 692,513
+toggle 857,470 through 950,528
+turn off 736,196 through 826,889
+turn on 17,878 through 850,987
+turn on 142,968 through 169,987
+turn on 46,470 through 912,853
+turn on 182,252 through 279,941
+toggle 261,143 through 969,657
+turn off 69,600 through 518,710
+turn on 372,379 through 779,386
+toggle 867,391 through 911,601
+turn off 174,287 through 900,536
+toggle 951,842 through 993,963
+turn off 626,733 through 985,827
+toggle 622,70 through 666,291
+turn off 980,671 through 985,835
+turn off 477,63 through 910,72
+turn off 779,39 through 940,142
+turn on 986,570 through 997,638
+toggle 842,805 through 943,985
+turn off 890,886 through 976,927
+turn off 893,172 through 897,619
+turn off 198,780 through 835,826
+toggle 202,209 through 219,291
+turn off 193,52 through 833,283
+toggle 414,427 through 987,972
+turn on 375,231 through 668,236
+turn off 646,598 through 869,663
+toggle 271,462 through 414,650
+turn off 679,121 through 845,467
+toggle 76,847 through 504,904
+turn off 15,617 through 509,810
+toggle 248,105 through 312,451
+turn off 126,546 through 922,879
+turn on 531,831 through 903,872
+toggle 602,431 through 892,792
+turn off 795,223 through 892,623
+toggle 167,721 through 533,929
+toggle 813,251 through 998,484
+toggle 64,640 through 752,942
+turn on 155,955 through 892,985
+turn on 251,329 through 996,497
+turn off 341,716 through 462,994
+toggle 760,127 through 829,189
+turn on 86,413 through 408,518
+toggle 340,102 through 918,558
+turn off 441,642 through 751,889
+turn on 785,292 through 845,325
+turn off 123,389 through 725,828
+turn on 905,73 through 983,270
+turn off 807,86 through 879,276
+toggle 500,866 through 864,916
+turn on 809,366 through 828,534
+toggle 219,356 through 720,617
+turn off 320,964 through 769,990
+turn off 903,167 through 936,631
+toggle 300,137 through 333,693
+toggle 5,675 through 755,848
+turn off 852,235 through 946,783
+toggle 355,556 through 941,664
+turn on 810,830 through 867,891
+turn off 509,869 through 667,903
+toggle 769,400 through 873,892
+turn on 553,614 through 810,729
+turn on 179,873 through 589,962
+turn off 466,866 through 768,926
+toggle 143,943 through 465,984
+toggle 182,380 through 569,552
+turn off 735,808 through 917,910
+turn on 731,802 through 910,847
+turn off 522,74 through 731,485
+turn on 444,127 through 566,996
+turn off 232,962 through 893,979
+turn off 231,492 through 790,976
+turn on 874,567 through 943,684
+toggle 911,840 through 990,932
+toggle 547,895 through 667,935
+turn off 93,294 through 648,636
+turn off 190,902 through 532,970
+turn off 451,530 through 704,613
+toggle 936,774 through 937,775
+turn off 116,843 through 533,934
+turn on 950,906 through 986,993
+turn on 910,51 through 945,989
+turn on 986,498 through 994,945
+turn off 125,324 through 433,704
+turn off 60,313 through 75,728
+turn on 899,494 through 940,947
+toggle 832,316 through 971,817
+toggle 994,983 through 998,984
+toggle 23,353 through 917,845
+toggle 174,799 through 658,859
+turn off 490,878 through 534,887
+turn off 623,963 through 917,975
+toggle 721,333 through 816,975
+toggle 589,687 through 890,921
+turn on 936,388 through 948,560
+turn off 485,17 through 655,610
+turn on 435,158 through 689,495
+turn on 192,934 through 734,936
+turn off 299,723 through 622,847
+toggle 484,160 through 812,942
+turn off 245,754 through 818,851
+turn on 298,419 through 824,634
+toggle 868,687 through 969,760
+toggle 131,250 through 685,426
+turn off 201,954 through 997,983
+turn on 353,910 through 832,961
+turn off 518,781 through 645,875
+turn off 866,97 through 924,784
+toggle 836,599 through 857,767
+turn on 80,957 through 776,968
+toggle 277,130 through 513,244
+turn off 62,266 through 854,434
+turn on 792,764 through 872,842
+turn off 160,949 through 273,989
+turn off 664,203 through 694,754
+toggle 491,615 through 998,836
+turn off 210,146 through 221,482
+turn off 209,780 through 572,894
+turn on 766,112 through 792,868
+turn on 222,12 through 856,241
diff --git a/native/solutions/2015/06/part_1.zig b/native/solutions/2015/06/part_1.zig
index 9eb7b4d..c028514 100644
--- a/native/solutions/2015/06/part_1.zig
+++ b/native/solutions/2015/06/part_1.zig
@@ -1,136 +1,118 @@
 const std = @import("std");
-const tools = @import("tools");
 
+const common = @import("./common.zig");
+
+const Action = common.Action;
 const Allocator = std.mem.Allocator;
 const AnyReader = std.io.AnyReader;
-const LineParser = tools.LineParser;
-
-const Action = enum { on, off, toggle };
-const Command = struct {
-    action: Action,
-
-    from_x: u16,
-    from_y: u16,
-
-    to_x: u16,
-    to_y: u16,
-};
+const Command = common.Command;
+const Parser = common.Parser;
 
-const State = enum { action, from_x, delimiter, from_y, through, to_x, to_y };
+const width = 1000;
+const height = 1000;
 
-const turn_on_pattern = "turn on ";
-const turn_off_pattern = "turn off ";
-const toggle_pattern = "toggle ";
-const through_pattern = "through ";
+fn allocLights(allocator: Allocator) ![]bool {
+    const lights = try allocator.alloc(bool, width * height);
 
-// NOTE: Minimal length of line, which pattern is:
-//
-//         turn off x,y through x,y
-//
-//       where `x` and `y` is number in range 0..9.
-const min_line_len =
-    turn_off_pattern.len + 3 + through_pattern.len + 3;
-
-fn isMatch(line: []const u8, comptime pattern: []const u8) bool {
-    if (line.len < pattern.len) {
-        return false;
+    for (lights) |*light| {
+        light.* = false;
     }
 
-    return std.mem.eql(u8, line[0..pattern.len], pattern);
+    return lights;
 }
 
-fn matchAction(line: []const u8) ?Action {
-    if (isMatch(line, turn_on_pattern)) {
-        return .on;
-    }
+inline fn turnOn(lights: []bool, from_x: usize, from_y: usize, to_x: usize, to_y: usize) void {
+    for (from_x..to_x + 1) |x| {
+        const from = x * 999 + from_y;
+        const to = from + (to_y - from_y) + 1;
 
-    if (isMatch(line, turn_off_pattern)) {
-        return .off;
+        for (from..to) |idx| {
+            lights[idx] = true;
+        }
     }
-
-    if (isMatch(line, toggle_pattern)) {
-        return .toggle;
-    }
-
-    return null;
 }
 
-fn parse(line: []const u8, allocator: Allocator) !Command {
-    if (line.len < min_line_len) {
-        return error.InvalidInput;
-    }
+inline fn turnOff(lights: []bool, from_x: usize, from_y: usize, to_x: usize, to_y: usize) void {
+    for (from_x..to_x + 1) |x| {
+        const from = x * 999 + from_y;
+        const to = from + (to_y - from_y) + 1;
 
-    const action = matchAction(line) orelse return error.InvalidInput;
-
-    var stream = std.io.fixedBufferStream(line);
-    const reader = stream.reader();
-
-    switch (action) {
-        .on => {
-            try reader.skipBytes(turn_on_pattern.len, .{});
-        },
-        .off => {
-            try reader.skipBytes(turn_off_pattern.len, .{});
-        },
-        .toggle => {
-            try reader.skipBytes(toggle_pattern.len, .{});
-        },
+        for (from..to) |idx| {
+            lights[idx] = false;
+        }
     }
+}
 
-    const from_x_buffer = try reader.readUntilDelimiterAlloc(allocator, ',', 4);
-    defer allocator.free(from_x_buffer);
-
-    const from_x = try std.fmt.parseInt(u16, from_x_buffer, 10);
-
-    const from_y_buffer = try reader.readUntilDelimiterAlloc(allocator, ' ', 4);
-    defer allocator.free(from_y_buffer);
-
-    const from_y = try std.fmt.parseInt(u16, from_y_buffer, 10);
-
-    const through_buffer = try allocator.alloc(u8, through_pattern.len);
-    defer allocator.free(through_buffer);
-
-    _ = try reader.read(through_buffer);
+inline fn toggle(lights: []bool, from_x: usize, from_y: usize, to_x: usize, to_y: usize) void {
+    for (from_x..to_x + 1) |x| {
+        const from = x * 999 + from_y;
+        const to = from + (to_y - from_y) + 1;
 
-    if (!isMatch(through_buffer, through_pattern)) {
-        return error.InvalidInput;
+        for (from..to) |idx| {
+            lights[idx] = !lights[idx];
+        }
     }
+}
 
-    const to_x_buffer = try reader.readUntilDelimiterAlloc(allocator, ',', 4);
-    defer allocator.free(to_x_buffer);
-
-    const to_x = try std.fmt.parseInt(u16, to_x_buffer, 10);
-
-    const to_y_buffer = try reader.readAllAlloc(allocator, 3);
-    defer allocator.free(to_y_buffer);
-
-    const to_y = try std.fmt.parseInt(u16, to_y_buffer, 10);
+pub fn solve(allocator: Allocator, reader: AnyReader) ![]const u8 {
+    var parser = Parser.init(allocator, reader);
+
+    const lights = try allocLights(allocator);
+    defer allocator.free(lights);
+
+    while (parser.read()) |command| {
+        switch (command.action) {
+            .on => {
+                turnOn(
+                    lights,
+                    command.from_x,
+                    command.from_y,
+                    command.to_x,
+                    command.to_y,
+                );
+            },
+            .off => {
+                turnOff(
+                    lights,
+                    command.from_x,
+                    command.from_y,
+                    command.to_x,
+                    command.to_y,
+                );
+            },
+            .toggle => {
+                toggle(
+                    lights,
+                    command.from_x,
+                    command.from_y,
+                    command.to_x,
+                    command.to_y,
+                );
+            },
+        }
+    } else |err| {
+        if (err != error.EndOfStream) {
+            return err;
+        }
+    }
 
-    return .{
-        .action = action,
+    var count: usize = 0;
 
-        .from_x = from_x,
-        .from_y = from_y,
+    for (lights) |light| {
+        if (light) {
+            count += 1;
+        }
+    }
 
-        .to_x = to_x,
-        .to_y = to_y,
-    };
+    return try std.fmt.allocPrint(allocator, "{d}", .{count});
 }
 
-pub fn solve(allocator: Allocator, _: AnyReader) ![]const u8 {
-    const action = try parse("turn on 599,989 through 806,993", allocator);
+test "solution 2015/06/01" {
+    const input_file = @embedFile("./input.fixture");
+    var input = std.io.fixedBufferStream(input_file);
 
-    std.log.info("{}", .{action});
+    const answer = try solve(std.testing.allocator, input.reader().any());
+    defer std.testing.allocator.free(answer);
 
-    return try std.fmt.allocPrint(allocator, "{d}", .{1});
+    try std.testing.expectEqualStrings(answer, "543903");
 }
-
-// test "solution 2015/05/01" {
-//     const input_file = @embedFile("./input.fixture");
-//     var input = std.io.fixedBufferStream(input_file);
-
-//     const answer = try solve(std.testing.allocator, input.reader().any());
-//     defer std.testing.allocator.free(answer);
-
-//     try std.testing.expectEqualStrings(answer, "238");
-// }
diff --git a/native/solutions/2015/06/part_2.zig b/native/solutions/2015/06/part_2.zig
new file mode 100644
index 0000000..7021fd3
--- /dev/null
+++ b/native/solutions/2015/06/part_2.zig
@@ -0,0 +1,118 @@
+const std = @import("std");
+
+const common = @import("./common.zig");
+
+const Action = common.Action;
+const Allocator = std.mem.Allocator;
+const AnyReader = std.io.AnyReader;
+const Command = common.Command;
+const Parser = common.Parser;
+
+const width = 1000;
+const height = 1000;
+
+fn allocLights(allocator: Allocator) ![]u16 {
+    const lights = try allocator.alloc(u16, width * height);
+
+    for (lights) |*light| {
+        light.* = 0;
+    }
+
+    return lights;
+}
+
+inline fn turnOn(lights: []u16, from_x: usize, from_y: usize, to_x: usize, to_y: usize) void {
+    for (from_x..to_x + 1) |x| {
+        const from = x * 999 + from_y;
+        const to = from + (to_y - from_y) + 1;
+
+        for (from..to) |idx| {
+            lights[idx] += 1;
+        }
+    }
+}
+
+inline fn turnOff(lights: []u16, from_x: usize, from_y: usize, to_x: usize, to_y: usize) void {
+    for (from_x..to_x + 1) |x| {
+        const from = x * 999 + from_y;
+        const to = from + (to_y - from_y) + 1;
+
+        for (from..to) |idx| {
+            if (lights[idx] > 0) {
+                lights[idx] -= 1;
+            }
+        }
+    }
+}
+
+inline fn toggle(lights: []u16, from_x: usize, from_y: usize, to_x: usize, to_y: usize) void {
+    for (from_x..to_x + 1) |x| {
+        const from = x * 999 + from_y;
+        const to = from + (to_y - from_y) + 1;
+
+        for (from..to) |idx| {
+            lights[idx] += 2;
+        }
+    }
+}
+
+pub fn solve(allocator: Allocator, reader: AnyReader) ![]const u8 {
+    var parser = Parser.init(allocator, reader);
+
+    const lights = try allocLights(allocator);
+    defer allocator.free(lights);
+
+    while (parser.read()) |command| {
+        switch (command.action) {
+            .on => {
+                turnOn(
+                    lights,
+                    command.from_x,
+                    command.from_y,
+                    command.to_x,
+                    command.to_y,
+                );
+            },
+            .off => {
+                turnOff(
+                    lights,
+                    command.from_x,
+                    command.from_y,
+                    command.to_x,
+                    command.to_y,
+                );
+            },
+            .toggle => {
+                toggle(
+                    lights,
+                    command.from_x,
+                    command.from_y,
+                    command.to_x,
+                    command.to_y,
+                );
+            },
+        }
+    } else |err| {
+        if (err != error.EndOfStream) {
+            return err;
+        }
+    }
+
+    var count: u32 = 0;
+
+    for (lights) |light| {
+        count += light;
+    }
+
+    return try std.fmt.allocPrint(allocator, "{d}", .{count});
+}
+
+test "solution 2015/06/02" {
+    const input_file = @embedFile("./input.fixture");
+    var input = std.io.fixedBufferStream(input_file);
+
+    const answer = try solve(std.testing.allocator, input.reader().any());
+    defer std.testing.allocator.free(answer);
+
+    try std.testing.expectEqualStrings(answer, "543903");
+}
diff --git a/native/solutions/registry.zig b/native/solutions/registry.zig
index e2c6d40..b046e27 100644
--- a/native/solutions/registry.zig
+++ b/native/solutions/registry.zig
@@ -81,6 +81,7 @@ pub const items = [_]Entry{
     entry(.year_2015, .day_05, .part_one, index.solver_2015_05_01),
     entry(.year_2015, .day_05, .part_two, index.solver_2015_05_02),
     entry(.year_2015, .day_06, .part_one, index.solver_2015_06_01),
+    entry(.year_2015, .day_06, .part_two, index.solver_2015_06_02),
 };
 
 pub fn lookup(year: Year, day: Day, part: Part) ?Solver {
diff --git a/native/solutions/solutions.zig b/native/solutions/solutions.zig
index edeeb88..f4ee43a 100644
--- a/native/solutions/solutions.zig
+++ b/native/solutions/solutions.zig
@@ -9,6 +9,7 @@ pub const solver_2015_04_02 = @import("./2015/04/part_2.zig").solve;
 pub const solver_2015_05_01 = @import("./2015/05/part_1.zig").solve;
 pub const solver_2015_05_02 = @import("./2015/05/part_2.zig").solve;
 pub const solver_2015_06_01 = @import("./2015/06/part_1.zig").solve;
+pub const solver_2015_06_02 = @import("./2015/06/part_2.zig").solve;
 
 test {
     @import("std").testing.refAllDecls(@This());