Solve day 5

src/day05.zig

@@ -0,0 +1,162 @@
+const std = @import("std");
+
+pub const input = @embedFile("input/day05.txt");
+const test_input = @embedFile("input/day05_test1.txt");
+
+var gpa = std.heap.GeneralPurposeAllocator(.{ .safety = true }){};
+const allocator = gpa.allocator();
+
+const Stack = std.SinglyLinkedList(u8);
+
+fn print_stacks(stacks: []Stack) void {
+    var i: usize = 0;
+    for (stacks) |stack| {
+        std.debug.print("{}: ", .{i + 1});
+        print_stack(stack);
+        i += 1;
+    }
+}
+
+fn print_stack(stack: Stack) void {
+    if (stack.first) |first| {
+        print_node(first);
+    } else {
+        std.debug.print("<empty>\n", .{});
+    }
+}
+
+fn print_node(node: *Stack.Node) void {
+    std.debug.print("{s}", .{&[_]u8{node.data}});
+    if (node.next) |next| {
+        std.debug.print(" -> ", .{});
+        print_node(next);
+    } else {
+        std.debug.print("\n", .{});
+    }
+}
+
+fn parse_stacks(lines: *std.mem.TokenIterator(u8)) ![9]Stack {
+    // TODO: is there a better way to initialize this?
+    var stacks: [9]Stack = [9]Stack{
+        Stack{},
+        Stack{},
+        Stack{},
+        Stack{},
+        Stack{},
+        Stack{},
+        Stack{},
+        Stack{},
+        Stack{},
+    };
+    while (lines.next()) |line| {
+        var i: usize = 0;
+        while (i < line.len) : (i += 4) {
+            const slot = line[i .. i + 3];
+            if (slot[0] == '[') {
+                const first = stacks[i / 4].first;
+                if (first) |f| {
+                    var new_node = try allocator.create(Stack.Node);
+                    new_node.* = Stack.Node{ .data = slot[1] };
+                    f.findLast().insertAfter(new_node);
+                } else {
+                    var new_node = try allocator.create(Stack.Node);
+                    new_node.* = Stack.Node{ .data = slot[1] };
+                    stacks[i / 4].prepend(new_node);
+                }
+            }
+        }
+    }
+    return stacks;
+}
+
+const Move = struct {
+    crates: usize,
+    from: usize,
+    to: usize,
+};
+
+fn parse_move(line: []const u8) !Move {
+    var parts = std.mem.tokenize(u8, line, " ");
+    _ = parts.next();
+    const crates = try std.fmt.parseInt(usize, parts.next().?, 10);
+    _ = parts.next();
+    const from = try std.fmt.parseInt(usize, parts.next().?, 10);
+    _ = parts.next();
+    const to = try std.fmt.parseInt(usize, parts.next().?, 10);
+    return Move{
+        .crates = crates,
+        .from = from - 1,
+        .to = to - 1,
+    };
+}
+
+fn get_top_crate_str(stacks: [9]Stack) ![]const u8 {
+    var message = std.ArrayList(u8).init(allocator);
+    var i: usize = 0;
+    while (i < 9) : (i += 1) {
+        if (stacks[i].first) |first| {
+            try message.append(first.data);
+        }
+    }
+    return message.toOwnedSlice();
+}
+
+pub fn solve_part1(data: []const u8) ![]const u8 {
+    var lines = std.mem.split(u8, data, "\n\n");
+
+    var stack_lines = std.mem.tokenize(u8, lines.next().?, "\n");
+    var stacks = try parse_stacks(&stack_lines);
+
+    var move_lines = std.mem.tokenize(u8, lines.next().?, "\n");
+    while (move_lines.next()) |line| {
+        const move = try parse_move(line);
+
+        var i: usize = 0;
+        while (i < move.crates) : (i += 1) {
+            const crate = stacks[move.from].popFirst().?;
+            stacks[move.to].prepend(crate);
+        }
+    }
+
+    return try get_top_crate_str(stacks);
+}
+
+pub fn solve_part2(data: []const u8) ![]const u8 {
+    var lines = std.mem.split(u8, data, "\n\n");
+
+    var stack_lines = std.mem.tokenize(u8, lines.next().?, "\n");
+    var stacks = try parse_stacks(&stack_lines);
+
+    var move_lines = std.mem.tokenize(u8, lines.next().?, "\n");
+    while (move_lines.next()) |line| {
+        const move = try parse_move(line);
+
+        // print_stacks(&stacks);
+        var i: usize = 0;
+        var temp = Stack{};
+        while (i < move.crates) : (i += 1) {
+            const crate = stacks[move.from].popFirst().?;
+            const first = temp.first;
+            if (first) |f| {
+                f.findLast().insertAfter(crate);
+            } else {
+                temp.prepend(crate);
+            }
+            // print_stack(temp);
+        }
+        if (stacks[move.to].first) |to_first| {
+            temp.first.?.findLast().next = to_first;
+        }
+        stacks[move.to].first = temp.first;
+    }
+
+    return try get_top_crate_str(stacks);
+}
+
+test "solves part1" {
+    try std.testing.expectEqualStrings(try solve_part1(test_input), "CMZ");
+}
+
+test "solves part2" {
+    try std.testing.expectEqualStrings(try solve_part2(test_input), "MCD");
+}

src/input/day05.txt

@@ -0,0 +1,511 @@
+[N]             [R]             [C]
+[T] [J]         [S] [J]         [N]
+[B] [Z]     [H] [M] [Z]         [D]
+[S] [P]     [G] [L] [H] [Z]     [T]
+[Q] [D]     [F] [D] [V] [L] [S] [M]
+[H] [F] [V] [J] [C] [W] [P] [W] [L]
+[G] [S] [H] [Z] [Z] [T] [F] [V] [H]
+[R] [H] [Z] [M] [T] [M] [T] [Q] [W]
+ 1   2   3   4   5   6   7   8   9 
+
+move 3 from 9 to 7
+move 4 from 4 to 5
+move 2 from 4 to 6
+move 4 from 7 to 5
+move 3 from 7 to 3
+move 2 from 5 to 9
+move 5 from 6 to 3
+move 5 from 9 to 1
+move 3 from 8 to 4
+move 3 from 4 to 6
+move 8 from 1 to 8
+move 1 from 8 to 6
+move 2 from 8 to 2
+move 5 from 8 to 4
+move 1 from 8 to 1
+move 6 from 6 to 4
+move 1 from 7 to 9
+move 5 from 1 to 7
+move 1 from 1 to 2
+move 2 from 9 to 8
+move 6 from 4 to 9
+move 1 from 6 to 8
+move 3 from 2 to 7
+move 4 from 2 to 8
+move 4 from 9 to 3
+move 6 from 5 to 4
+move 7 from 8 to 1
+move 10 from 4 to 1
+move 12 from 1 to 5
+move 1 from 4 to 9
+move 1 from 2 to 3
+move 2 from 9 to 1
+move 1 from 9 to 3
+move 1 from 6 to 7
+move 1 from 9 to 1
+move 3 from 1 to 3
+move 9 from 5 to 9
+move 2 from 2 to 7
+move 2 from 7 to 4
+move 3 from 9 to 4
+move 7 from 5 to 7
+move 5 from 1 to 3
+move 2 from 4 to 5
+move 1 from 4 to 6
+move 1 from 6 to 9
+move 4 from 9 to 2
+move 12 from 7 to 9
+move 2 from 4 to 9
+move 6 from 5 to 9
+move 3 from 7 to 6
+move 12 from 9 to 6
+move 5 from 9 to 1
+move 1 from 7 to 6
+move 14 from 6 to 1
+move 20 from 3 to 5
+move 5 from 9 to 5
+move 3 from 2 to 8
+move 1 from 6 to 4
+move 1 from 9 to 2
+move 1 from 4 to 6
+move 1 from 2 to 6
+move 16 from 1 to 5
+move 1 from 2 to 1
+move 12 from 5 to 6
+move 1 from 8 to 4
+move 29 from 5 to 1
+move 5 from 6 to 9
+move 20 from 1 to 3
+move 4 from 1 to 3
+move 11 from 3 to 8
+move 1 from 4 to 3
+move 4 from 9 to 8
+move 7 from 1 to 8
+move 2 from 3 to 2
+move 2 from 6 to 7
+move 1 from 9 to 8
+move 10 from 3 to 5
+move 1 from 6 to 1
+move 1 from 7 to 2
+move 3 from 1 to 2
+move 6 from 2 to 4
+move 2 from 6 to 3
+move 4 from 6 to 5
+move 1 from 6 to 2
+move 1 from 2 to 9
+move 6 from 5 to 2
+move 1 from 9 to 3
+move 24 from 8 to 7
+move 1 from 4 to 8
+move 5 from 5 to 4
+move 1 from 4 to 8
+move 1 from 8 to 7
+move 2 from 8 to 9
+move 1 from 9 to 7
+move 6 from 2 to 4
+move 10 from 3 to 7
+move 3 from 5 to 3
+move 1 from 9 to 8
+move 3 from 3 to 8
+move 4 from 8 to 7
+move 1 from 4 to 6
+move 1 from 6 to 4
+move 13 from 4 to 3
+move 17 from 7 to 6
+move 1 from 6 to 3
+move 2 from 4 to 8
+move 3 from 7 to 5
+move 14 from 6 to 7
+move 1 from 5 to 9
+move 1 from 5 to 9
+move 2 from 6 to 7
+move 1 from 5 to 1
+move 1 from 1 to 6
+move 1 from 9 to 3
+move 29 from 7 to 4
+move 10 from 4 to 3
+move 6 from 7 to 5
+move 1 from 6 to 5
+move 1 from 9 to 7
+move 1 from 7 to 2
+move 4 from 3 to 2
+move 1 from 2 to 9
+move 1 from 8 to 5
+move 11 from 3 to 4
+move 24 from 4 to 7
+move 2 from 2 to 5
+move 10 from 3 to 2
+move 6 from 2 to 1
+move 5 from 4 to 7
+move 1 from 9 to 2
+move 3 from 5 to 1
+move 1 from 4 to 6
+move 4 from 2 to 3
+move 5 from 5 to 7
+move 2 from 5 to 3
+move 32 from 7 to 5
+move 16 from 5 to 1
+move 1 from 1 to 2
+move 3 from 2 to 9
+move 1 from 8 to 6
+move 3 from 7 to 6
+move 1 from 2 to 4
+move 5 from 6 to 8
+move 5 from 8 to 6
+move 2 from 9 to 3
+move 1 from 7 to 5
+move 9 from 5 to 4
+move 1 from 9 to 1
+move 2 from 3 to 1
+move 4 from 3 to 6
+move 1 from 3 to 8
+move 6 from 4 to 6
+move 6 from 5 to 9
+move 1 from 9 to 6
+move 1 from 5 to 1
+move 1 from 5 to 4
+move 1 from 3 to 6
+move 1 from 8 to 3
+move 1 from 4 to 2
+move 1 from 2 to 3
+move 17 from 6 to 4
+move 4 from 1 to 8
+move 3 from 9 to 6
+move 1 from 8 to 4
+move 1 from 9 to 7
+move 2 from 6 to 2
+move 1 from 7 to 8
+move 12 from 1 to 9
+move 8 from 9 to 2
+move 1 from 6 to 9
+move 6 from 2 to 8
+move 2 from 8 to 3
+move 18 from 4 to 9
+move 2 from 1 to 6
+move 1 from 6 to 5
+move 3 from 4 to 3
+move 7 from 3 to 8
+move 4 from 2 to 7
+move 1 from 4 to 6
+move 2 from 6 to 4
+move 13 from 9 to 6
+move 1 from 5 to 2
+move 5 from 9 to 3
+move 9 from 1 to 2
+move 1 from 1 to 8
+move 1 from 2 to 6
+move 3 from 7 to 6
+move 2 from 2 to 6
+move 9 from 8 to 6
+move 1 from 7 to 8
+move 1 from 8 to 7
+move 2 from 4 to 6
+move 5 from 3 to 6
+move 17 from 6 to 9
+move 7 from 8 to 4
+move 4 from 2 to 3
+move 17 from 6 to 2
+move 1 from 6 to 4
+move 1 from 7 to 8
+move 1 from 8 to 9
+move 24 from 9 to 6
+move 4 from 3 to 1
+move 1 from 1 to 5
+move 20 from 6 to 4
+move 4 from 6 to 9
+move 1 from 5 to 7
+move 2 from 4 to 2
+move 1 from 9 to 7
+move 25 from 4 to 3
+move 1 from 4 to 2
+move 2 from 1 to 6
+move 3 from 9 to 4
+move 2 from 4 to 7
+move 2 from 7 to 5
+move 1 from 4 to 2
+move 1 from 6 to 3
+move 1 from 1 to 5
+move 5 from 3 to 9
+move 1 from 5 to 6
+move 10 from 2 to 8
+move 9 from 2 to 5
+move 21 from 3 to 6
+move 1 from 7 to 6
+move 2 from 6 to 5
+move 5 from 9 to 7
+move 6 from 7 to 8
+move 19 from 6 to 9
+move 1 from 6 to 1
+move 8 from 8 to 1
+move 1 from 6 to 1
+move 2 from 8 to 5
+move 5 from 9 to 2
+move 6 from 8 to 2
+move 2 from 9 to 7
+move 9 from 9 to 4
+move 7 from 2 to 4
+move 1 from 6 to 4
+move 14 from 5 to 9
+move 1 from 1 to 8
+move 1 from 7 to 9
+move 4 from 2 to 9
+move 16 from 4 to 6
+move 3 from 2 to 8
+move 1 from 6 to 2
+move 2 from 8 to 9
+move 1 from 8 to 7
+move 1 from 8 to 3
+move 3 from 2 to 7
+move 1 from 3 to 9
+move 8 from 9 to 3
+move 4 from 7 to 8
+move 1 from 5 to 4
+move 4 from 6 to 3
+move 1 from 4 to 2
+move 9 from 3 to 8
+move 10 from 9 to 5
+move 8 from 6 to 7
+move 13 from 8 to 4
+move 8 from 5 to 2
+move 3 from 6 to 3
+move 7 from 9 to 6
+move 7 from 7 to 2
+move 2 from 4 to 6
+move 5 from 6 to 2
+move 3 from 1 to 5
+move 5 from 5 to 8
+move 4 from 6 to 2
+move 4 from 1 to 8
+move 15 from 2 to 6
+move 11 from 4 to 9
+move 12 from 6 to 8
+move 1 from 6 to 9
+move 5 from 3 to 7
+move 2 from 2 to 6
+move 6 from 7 to 1
+move 3 from 1 to 3
+move 1 from 4 to 1
+move 1 from 3 to 9
+move 1 from 3 to 9
+move 1 from 7 to 6
+move 1 from 3 to 2
+move 4 from 2 to 6
+move 4 from 2 to 7
+move 1 from 2 to 6
+move 4 from 1 to 6
+move 12 from 6 to 7
+move 2 from 6 to 1
+move 8 from 9 to 6
+move 1 from 7 to 4
+move 14 from 8 to 1
+move 8 from 1 to 5
+move 1 from 3 to 9
+move 5 from 9 to 5
+move 1 from 8 to 9
+move 1 from 9 to 2
+move 1 from 9 to 3
+move 5 from 8 to 3
+move 12 from 5 to 4
+move 1 from 9 to 2
+move 6 from 7 to 3
+move 7 from 3 to 2
+move 1 from 5 to 1
+move 1 from 8 to 3
+move 2 from 1 to 3
+move 2 from 6 to 9
+move 5 from 6 to 5
+move 5 from 1 to 7
+move 4 from 4 to 1
+move 7 from 2 to 8
+move 4 from 3 to 8
+move 1 from 9 to 3
+move 1 from 9 to 5
+move 4 from 1 to 8
+move 10 from 7 to 9
+move 1 from 6 to 7
+move 2 from 8 to 6
+move 6 from 4 to 2
+move 5 from 3 to 1
+move 2 from 6 to 3
+move 2 from 7 to 1
+move 5 from 2 to 5
+move 2 from 7 to 1
+move 7 from 5 to 7
+move 2 from 5 to 6
+move 2 from 5 to 3
+move 3 from 2 to 9
+move 9 from 9 to 3
+move 1 from 6 to 4
+move 3 from 3 to 1
+move 9 from 8 to 2
+move 6 from 3 to 6
+move 8 from 7 to 9
+move 4 from 9 to 8
+move 14 from 1 to 5
+move 1 from 9 to 2
+move 1 from 1 to 5
+move 2 from 3 to 6
+move 12 from 5 to 3
+move 2 from 2 to 8
+move 7 from 6 to 2
+move 12 from 2 to 8
+move 2 from 6 to 2
+move 6 from 9 to 6
+move 1 from 1 to 2
+move 1 from 9 to 3
+move 2 from 5 to 9
+move 1 from 9 to 2
+move 1 from 9 to 4
+move 1 from 3 to 2
+move 2 from 6 to 7
+move 2 from 6 to 9
+move 5 from 4 to 2
+move 14 from 3 to 9
+move 15 from 9 to 4
+move 1 from 7 to 4
+move 10 from 8 to 6
+move 1 from 5 to 9
+move 2 from 9 to 5
+move 10 from 8 to 1
+move 1 from 7 to 4
+move 5 from 1 to 2
+move 2 from 1 to 5
+move 3 from 4 to 6
+move 4 from 5 to 8
+move 5 from 8 to 6
+move 14 from 2 to 9
+move 2 from 6 to 7
+move 3 from 2 to 9
+move 3 from 1 to 7
+move 1 from 7 to 3
+move 3 from 7 to 1
+move 1 from 3 to 6
+move 1 from 7 to 6
+move 1 from 8 to 9
+move 2 from 1 to 4
+move 1 from 1 to 2
+move 16 from 9 to 4
+move 7 from 4 to 8
+move 5 from 8 to 1
+move 2 from 8 to 3
+move 2 from 1 to 7
+move 13 from 6 to 7
+move 2 from 2 to 3
+move 4 from 7 to 4
+move 6 from 4 to 5
+move 4 from 7 to 6
+move 3 from 1 to 2
+move 2 from 2 to 6
+move 3 from 3 to 8
+move 5 from 5 to 3
+move 2 from 9 to 6
+move 3 from 3 to 7
+move 1 from 8 to 1
+move 22 from 4 to 8
+move 1 from 4 to 3
+move 9 from 6 to 3
+move 1 from 2 to 1
+move 4 from 3 to 4
+move 2 from 4 to 5
+move 1 from 1 to 7
+move 4 from 3 to 7
+move 2 from 6 to 1
+move 1 from 6 to 7
+move 18 from 8 to 7
+move 2 from 6 to 5
+move 2 from 3 to 4
+move 1 from 5 to 4
+move 30 from 7 to 6
+move 2 from 1 to 3
+move 18 from 6 to 8
+move 12 from 6 to 4
+move 13 from 4 to 9
+move 2 from 3 to 8
+move 1 from 6 to 2
+move 3 from 7 to 2
+move 1 from 1 to 2
+move 2 from 5 to 9
+move 8 from 8 to 1
+move 1 from 7 to 8
+move 7 from 1 to 3
+move 2 from 4 to 9
+move 1 from 1 to 6
+move 4 from 2 to 1
+move 16 from 8 to 1
+move 1 from 2 to 6
+move 2 from 4 to 8
+move 2 from 5 to 1
+move 4 from 3 to 7
+move 3 from 7 to 1
+move 1 from 6 to 8
+move 1 from 8 to 9
+move 1 from 7 to 3
+move 6 from 3 to 5
+move 1 from 3 to 8
+move 1 from 6 to 9
+move 16 from 9 to 5
+move 4 from 5 to 3
+move 15 from 5 to 1
+move 1 from 5 to 8
+move 3 from 9 to 8
+move 9 from 8 to 5
+move 6 from 5 to 1
+move 4 from 5 to 6
+move 2 from 6 to 4
+move 1 from 6 to 4
+move 1 from 8 to 4
+move 3 from 3 to 6
+move 3 from 6 to 8
+move 1 from 6 to 8
+move 21 from 1 to 9
+move 4 from 8 to 5
+move 3 from 5 to 7
+move 2 from 5 to 1
+move 2 from 4 to 8
+move 2 from 8 to 2
+move 2 from 7 to 8
+move 1 from 7 to 9
+move 1 from 8 to 7
+move 5 from 1 to 8
+move 1 from 7 to 8
+move 4 from 8 to 4
+move 2 from 4 to 5
+move 1 from 2 to 7
+move 1 from 2 to 7
+move 2 from 7 to 6
+move 2 from 6 to 9
+move 1 from 4 to 9
+move 1 from 3 to 4
+move 16 from 1 to 5
+move 16 from 5 to 7
+move 2 from 5 to 4
+move 14 from 9 to 6
+move 5 from 4 to 3
+move 3 from 3 to 6
+move 5 from 1 to 4
+move 2 from 4 to 7
+move 7 from 9 to 4
+move 2 from 9 to 7
+move 10 from 6 to 9
+move 8 from 4 to 6
+move 1 from 8 to 4
+move 1 from 1 to 9
+move 14 from 6 to 3
+move 10 from 3 to 2
+move 3 from 7 to 8
+move 6 from 3 to 1
+move 2 from 7 to 9
+move 5 from 7 to 9
+move 10 from 9 to 1
+move 2 from 4 to 3
+move 1 from 2 to 1
+move 16 from 1 to 4
+move 1 from 6 to 1
+move 2 from 3 to 9
+move 3 from 8 to 5
+move 8 from 7 to 1
+move 3 from 5 to 9
+move 7 from 4 to 6
+move 7 from 1 to 5
+move 2 from 8 to 3
+move 1 from 7 to 8

src/input/day05_test1.txt

@@ -0,0 +1,9 @@
+    [D]    
+[N] [C]    
+[Z] [M] [P]
+ 1   2   3 
+
+move 1 from 2 to 1
+move 3 from 1 to 3
+move 2 from 2 to 1
+move 1 from 1 to 2

src/main.zig

@@ -4,6 +4,7 @@ const day01 = @import("day01.zig");
 const day02 = @import("day02.zig");
 const day03 = @import("day03.zig");
 const day04 = @import("day04.zig");
+const day05 = @import("day05.zig");
 const utils = @import("utils.zig");
 
 fn solve_day(comptime day_num: u8, day: anytype, stdout: anytype, timer: *std.time.Timer) !void {
@@ -13,13 +14,21 @@ fn solve_day(comptime day_num: u8, day: anytype, stdout: anytype, timer: *std.ti
     var part1 = try day.solve_part1(day.input);
     const part1_end = timer.read();
     const part1_time = utils.HumanTime.new(part1_end - part1_start);
+    if (@TypeOf(part1) == []const u8) {
+        try stdout.print("Part 1: {s} ({d:.2} {s})\n", .{ part1, part1_time.value, part1_time.unit.abbr() });
+    } else {
         try stdout.print("Part 1: {} ({d:.2} {s})\n", .{ part1, part1_time.value, part1_time.unit.abbr() });
+    }
 
     const part2_start = timer.read();
     var part2 = try day.solve_part2(day.input);
     const part2_end = timer.read();
     const part2_time = utils.HumanTime.new(part2_end - part2_start);
+    if (@TypeOf(part2) == []const u8) {
+        try stdout.print("Part 2: {s} ({d:.2} {s})\n", .{ part2, part2_time.value, part2_time.unit.abbr() });
+    } else {
         try stdout.print("Part 2: {} ({d:.2} {s})\n", .{ part2, part2_time.value, part2_time.unit.abbr() });
+    }
 }
 
 pub fn main() !void {
@@ -32,6 +41,7 @@ pub fn main() !void {
     try solve_day(2, day02, &stdout, &timer);
     try solve_day(3, day03, &stdout, &timer);
     try solve_day(4, day04, &stdout, &timer);
+    try solve_day(5, day05, &stdout, &timer);
 
     try bw.flush();
 }
@@ -43,5 +53,6 @@ test {
     _ = day02;
     _ = day03;
     _ = day04;
+    _ = day05;
     _ = utils;
 }