day_06.zig


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const std = @import("std");
const Result = @import("util/aoc.zig").Result;

pub fn puzzle_1(input: []const u8) Result {
    var iter = std.mem.split(u8, input, "\n");

    var i: usize = 0;
    mainLoop: while (iter.next()) |line| {
        var buf = std.mem.zeroes([4]u32);
        var buf_idx: usize = 0;
        for (line) |c, idx| {
            if (buf_idx > 3) buf_idx = 0;
            buf[buf_idx] = @as(u32, 1) << @intCast(u5, c - 97); // 97 == 'a'
            buf_idx += 1;
            if (@popCount(buf[0] | buf[1] | buf[2] | buf[3]) == 4) {
                i = idx + 1;
                break :mainLoop;
            }
        }
    }

    return .{ .int = @intCast(i32, i) };
}

pub fn puzzle_2(input: []const u8) Result {
    var iter = std.mem.split(u8, input, "\n");

    var i: usize = 0;
    mainLoop: while (iter.next()) |line| {
        var buf = std.mem.zeroes([14]u32);
        var buf_idx: usize = 0;
        for (line) |c, idx| {
            if (buf_idx > 13) buf_idx = 0;
            buf[buf_idx] = @as(u32, 1) << @intCast(u5, c - 97); // 97 == 'a'
            buf_idx += 1;

            const hammer: u32 = blk: {
                var hidx: usize = 0;
                var tmp: u32 = 0;
                while (hidx < 14) : (hidx += 1) tmp |= buf[hidx];
                break :blk tmp;
            };

            if (@popCount(hammer) == 14) {
                i = idx + 1;
                break :mainLoop;
            }
        }
    }

    return .{ .int = @intCast(i32, i) };
}