From ca849239902668b47c4592ed7a7061e905de301e Mon Sep 17 00:00:00 2001 From: xeals Date: Fri, 8 Dec 2023 16:46:26 +1100 Subject: [PATCH] day08 part1 --- src/day08.zig | 75 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 75 insertions(+) create mode 100644 src/day08.zig diff --git a/src/day08.zig b/src/day08.zig new file mode 100644 index 0000000..94d0ce0 --- /dev/null +++ b/src/day08.zig @@ -0,0 +1,75 @@ +const std = @import("std"); +const util = @import("util.zig"); +const mem = std.mem; + +pub fn main() !void { + const input = @embedFile("data/day08.txt"); + const sln = try solve(util.gpa, input); + std.debug.print("{d}\n", .{sln.a}); + std.debug.print("{d}\n", .{sln.b}); +} + +const Solution = struct { + a: usize, + b: usize, +}; + +const Step = struct { + left: [3]u8, + right: [3]u8, +}; + +fn solve(alloc: mem.Allocator, input: []const u8) !Solution { + var states = std.AutoHashMap([3]u8, Step).init(alloc); + defer states.deinit(); + + var position: [3]u8 = "AAA".*; + + var it = util.splitLines(input); + const steps = it.next().?; + while (it.next()) |line| { + if (line.len == 0) continue; + try states.put(line[0..3].*, .{ .left = line[7..10].*, .right = line[12..15].* }); + } + + var count: u16 = 0; + while (!mem.eql(u8, &position, "ZZZ")) : (count += 1) { + const currState = states.get(position) orelse break; // ??????? + position = if (steps[count % steps.len] == 'L') currState.left else currState.right; + } + + return .{ .a = count, .b = 0 }; +} + +test "silver" { + const input = + \\RL + \\ + \\AAA = (BBB, CCC) + \\BBB = (DDD, EEE) + \\CCC = (ZZZ, GGG) + \\DDD = (DDD, DDD) + \\EEE = (EEE, EEE) + \\GGG = (GGG, GGG) + \\ZZZ = (ZZZ, ZZZ) + ; + const sln = try solve(std.testing.allocator, input); + try std.testing.expectEqual(@as(usize, 2), sln.a); +} + +test "gold" { + const input = + \\LR + \\ + \\11A = (11B, XXX) + \\11B = (XXX, 11Z) + \\11Z = (11B, XXX) + \\22A = (22B, XXX) + \\22B = (22C, 22C) + \\22C = (22Z, 22Z) + \\22Z = (22B, 22B) + \\XXX = (XXX, XXX) + ; + const sln = try solve(std.testing.allocator, input); + try std.testing.expectEqual(@as(usize, 0), sln.b); +}