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const std = @import("std");
const example = @embedFile("example");
const input = @embedFile("input");
var allocator: std.mem.Allocator = undefined;
pub fn main() anyerror!void {
var arena = std.heap.ArenaAllocator.init(std.heap.page_allocator);
defer arena.deinit();
allocator = arena.allocator();
try std.testing.expectEqual(try solve(example), 140);
const result = try solve(input);
try std.io.getStdOut().writer().print("{}\n", .{result});
}
const ListErrors = error{
OutOfMemory,
};
const List = struct {
data: std.ArrayList(Elt),
fn addOne(l: *List) !*Elt {
return try l.data.addOne();
}
fn init(reader: anytype) !*List {
var l = try allocator.create(List);
l.data = std.ArrayList(Elt).init(allocator);
while (true) {
const c = reader.readByte() catch break;
switch (c) {
'[' => {
var e = try l.data.addOne();
e.* = Elt{ .list = try List.init(reader) };
},
']' => {
return l;
},
',' => { // comma after a list ending, ignore
},
else => { // a digit
var e = try l.data.addOne();
e.* = Elt{ .int = c - '0' };
while (true) {
const d = reader.readByte() catch unreachable;
if (d == ']') {
return l;
} else if (d == ',') {
break;
}
e.int = e.int * 10 + d;
}
},
}
}
return l;
}
fn initEmpty() !*List {
var l = try allocator.create(List);
l.data = std.ArrayList(Elt).init(allocator);
return l;
}
fn initSingleton(n: u8) !*List {
var l = try allocator.create(List);
l.data = std.ArrayList(Elt).init(allocator);
var e = try l.data.addOne();
e.* = Elt{ .int = n };
return l;
}
fn isLowerThan(l: *List, o: *List) ListErrors!?bool {
var i: usize = 0;
while (true) : (i += 1) {
if (o.len() <= i) {
if (l.len() <= i) {
return null;
}
return false;
}
if (l.len() <= i) {
return true;
}
const t = try l.data.items[i].isLowerThan(&(o.data.items[i]));
if (t != null) {
return t;
}
}
}
inline fn len(l: *List) usize {
return l.data.items.len;
}
fn print(l: *List) void {
for (l.data.items) |e| {
switch (e) {
Elt.int => |i| std.debug.print("{d} ", .{i}),
Elt.list => |o| {
std.debug.print("[", .{});
o.print();
std.debug.print("]", .{});
},
}
}
}
};
const EltType = enum {
int,
list,
};
const Elt = union(EltType) {
int: u8,
list: *List,
fn isLowerThan(e: *Elt, f: *Elt) !?bool {
switch (e.*) {
Elt.int => |i| switch (f.*) {
Elt.int => |j| {
if (i == j) {
return null;
}
return i < j;
},
Elt.list => |o| {
var l = try List.initSingleton(i);
return l.isLowerThan(o);
},
},
Elt.list => |l| switch (f.*) {
Elt.int => |j| {
var ll = Elt{ .list = try List.initSingleton(j) };
return e.isLowerThan(&ll);
},
Elt.list => |o| {
return l.isLowerThan(o);
},
},
}
}
};
fn lesserThan(context: void, a: *Elt, b: *Elt) bool {
_ = context;
var tt = a.isLowerThan(b) catch unreachable;
if (tt) |t| {
if (t) {
return true;
}
}
return false;
}
fn solve(puzzle: []const u8) !u64 {
var it = std.mem.tokenize(u8, puzzle, "\n");
var list = std.ArrayList(*Elt).init(allocator);
var divider2Line = std.io.fixedBufferStream("[[2]]");
var div2 = try list.addOne();
div2.* = try allocator.create(Elt);
div2.*.* = Elt{ .list = try List.init(divider2Line.reader()) };
var divider6Line = std.io.fixedBufferStream("[[6]]");
var div6 = try list.addOne();
div6.* = try allocator.create(Elt);
div6.*.* = Elt{ .list = try List.init(divider6Line.reader()) };
// process input
while (it.next()) |line| {
var bs = std.io.fixedBufferStream(line);
var elt = try list.addOne();
elt.* = try allocator.create(Elt);
elt.*.* = Elt{ .list = try List.init(bs.reader()) };
}
// sort the list
std.sort.sort(*Elt, list.items, {}, lesserThan);
//for (list.items) |l| {
// l.list.print();
// std.debug.print("\n", .{});
//}
// compute output
var ret: usize = 1;
for (list.items) |l, i| {
switch (l.*) {
Elt.int => {},
Elt.list => |ll| {
if (ll.len() != 1) {
continue;
}
switch (ll.data.items[0]) {
Elt.int => {},
Elt.list => |lll| {
if (lll.len() != 1) {
continue;
}
switch (lll.data.items[0]) {
Elt.int => {},
Elt.list => |llll| {
if (llll.len() != 1) {
continue;
}
switch (llll.data.items[0]) {
Elt.int => |n| {
if (n == 2 or n == 6) {
ret *= (i + 1);
}
},
Elt.list => {},
}
},
}
},
}
},
}
}
return ret;
}
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