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2024-12-03 02:40:17 -06:00
parent 398a587d95
commit 012e963b48
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03/src/main.zig Normal file
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// Day 3! I chose the worst way to do this and then stuck with it
// Also zig is hell I want rust...
const std = @import("std");
var arena = std.heap.ArenaAllocator.init(std.heap.page_allocator);
const alloc = arena.allocator();
const test_data = @embedFile("test");
const test_data2 = @embedFile("test2");
const input_data = @embedFile("input");
pub fn main() !void {
const stdout = std.io.getStdOut().writer();
const value1 = try run1(input_data);
try stdout.print("{d}\n", .{value1});
const value2 = try run2(input_data);
try stdout.print("{d}\n", .{value2});
}
test "test input part 1" {
const value = try run1(test_data);
std.debug.print("{d}\n", .{value});
try std.testing.expectEqual(value, 161);
}
test "test input part 2" {
const value = try run2(test_data2);
std.debug.print("{d}\n", .{value});
try std.testing.expectEqual(value, 48);
}
const STATE = enum { waiting, m, u, l, open, d, o, n, open_do, close_do, apo, t, open_dont, close_dont, rewind };
fn integerUntilDelimiter(reader: anytype, writer: anytype, delimiter: u8, optional_max_size: ?usize) anyerror!void {
if (optional_max_size) |max_size| {
for (0..max_size) |_| {
const byte: u8 = try reader.readByte();
if (byte == delimiter) return;
if (byte < '0' or byte > '9') return error.BadCharacter;
try writer.writeByte(byte);
}
return error.StreamTooLong;
} else {
while (true) {
const byte: u8 = try reader.readByte();
if (byte == delimiter) return;
try writer.writeByte(byte);
}
// Can not throw `error.StreamTooLong` since there are no boundary.
}
}
fn run2(s: []const u8) !u64 {
// zig doesn't have regex
// sobs
var s_fbs = std.io.fixedBufferStream(s);
var reader = s_fbs.reader();
var state = STATE.waiting;
var buf: [1024]u8 = undefined;
var total: u64 = 0;
var do_mul: bool = true;
// i tried a state machine.
// god i don't know zig at all
// this is so genuinely awful
read: while (true) {
// state transition
state = sw: {
break :sw switch (state) {
STATE.rewind => {
try s_fbs.seekBy(-1);
break :sw STATE.waiting;
},
STATE.waiting => {
switch (reader.readByte() catch {
break :read;
}) {
'm' => {
break :sw STATE.m;
},
'd' => {
break :sw STATE.d;
},
else => {
break :sw STATE.waiting;
},
}
},
STATE.m => if (reader.readByte() catch {
break :read;
} == 'u') STATE.u else STATE.rewind,
STATE.u => if (reader.readByte() catch {
break :read;
} == 'l') STATE.l else STATE.rewind,
STATE.l => if (reader.readByte() catch {
break :read;
} == '(') STATE.open else STATE.rewind,
STATE.d => if (reader.readByte() catch {
break :read;
} == 'o') STATE.o else STATE.rewind,
STATE.o => switch (reader.readByte() catch {
break :read;
}) {
'n' => STATE.n,
'(' => STATE.open_do,
else => STATE.rewind,
},
STATE.open_do => if (reader.readByte() catch {
break :read;
} == ')') STATE.close_do else STATE.rewind,
STATE.n => if (reader.readByte() catch {
break :read;
} == '\'') STATE.apo else STATE.rewind,
STATE.apo => if (reader.readByte() catch {
break :read;
} == 't') STATE.t else STATE.rewind,
STATE.t => if (reader.readByte() catch {
break :read;
} == '(') STATE.open_dont else STATE.rewind,
STATE.open_dont => if (reader.readByte() catch {
break :read;
} == ')') STATE.close_dont else STATE.rewind,
STATE.close_do => {
do_mul = true;
break :sw STATE.waiting;
},
STATE.close_dont => {
do_mul = false;
break :sw STATE.waiting;
},
STATE.open => {
var fbs = std.io.fixedBufferStream(&buf);
integerUntilDelimiter(reader, fbs.writer(), ',', 1024) catch {
state = STATE.waiting;
continue :read;
};
const num0 = std.fmt.parseInt(u64, fbs.getWritten(), 10) catch {
state = STATE.waiting;
continue :read;
};
fbs = std.io.fixedBufferStream(&buf);
integerUntilDelimiter(reader, fbs.writer(), ')', 1024) catch {
state = STATE.waiting;
continue :read;
};
const num1 = std.fmt.parseInt(u64, fbs.getWritten(), 10) catch {
state = STATE.waiting;
continue :read;
};
if (do_mul) {
std.debug.print("{d} {d}\n", .{ num0, num1 });
total += num0 * num1;
}
break :sw STATE.waiting;
},
};
};
}
return total;
}
fn run1(s: []const u8) !u64 {
// zig doesn't have regex
// sobs
var s_fbs = std.io.fixedBufferStream(s);
var reader = s_fbs.reader();
var state = STATE.waiting;
var buf: [1024]u8 = undefined;
var total: u64 = 0;
// i tried a state machine.
// god i don't know zig at all
// this is so genuinely awful
read: while (true) {
// state transition
state = sw: {
break :sw switch (state) {
STATE.waiting => if (reader.readByte() catch {
break :read;
} == 'm') STATE.m else STATE.waiting,
STATE.m => if (reader.readByte() catch {
break :read;
} == 'u') STATE.u else STATE.waiting,
STATE.u => if (reader.readByte() catch {
break :read;
} == 'l') STATE.l else STATE.waiting,
STATE.l => if (reader.readByte() catch {
break :read;
} == '(') STATE.open else STATE.waiting,
STATE.open => {
var fbs = std.io.fixedBufferStream(&buf);
integerUntilDelimiter(reader, fbs.writer(), ',', 1024) catch {
state = STATE.waiting;
continue :read;
};
const num0 = std.fmt.parseInt(u64, fbs.getWritten(), 10) catch {
state = STATE.waiting;
continue :read;
};
fbs = std.io.fixedBufferStream(&buf);
integerUntilDelimiter(reader, fbs.writer(), ')', 1024) catch {
state = STATE.waiting;
continue :read;
};
const num1 = std.fmt.parseInt(u64, fbs.getWritten(), 10) catch {
state = STATE.waiting;
continue :read;
};
std.debug.print("{d} {d}\n", .{ num0, num1 });
total += num0 * num1;
break :sw STATE.waiting;
},
else => STATE.waiting,
};
};
}
return total;
}