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const std = @import("std");
const Result = @import("util/aoc.zig").Result;
const Operation = struct {
symbol: u8,
fixed: bool = false,
fixed_number: u8 = 0,
fn exe(self: Operation, b: u64) u64 {
if (self.symbol == '*') {
switch (self.fixed) {
true => return self.fixed_number * b,
false => return b * b,
}
}
switch (self.fixed) {
true => return self.fixed_number + b,
false => return b + b,
}
}
};
const Monkey = struct {
const Throw_rules = struct {
multiple_of: u8,
true: u8,
false: u8,
};
id: u8,
inspect_count: usize = 0,
items: std.ArrayList(u64),
operation: Operation,
throw_rules: Throw_rules,
fn throws_to(self: Monkey, worry_level: u64) usize {
if (worry_level % self.throw_rules.multiple_of == 0) return self.throw_rules.true;
return self.throw_rules.false;
}
fn inspect(self: *Monkey) u64 {
self.inspect_count += 1;
return self.operation.exe(self.items.orderedRemove(0));
}
};
fn answer(monkeys: []Monkey) u64 {
var max: [2]u64 = std.mem.zeroes([2]u64);
for (monkeys) |*monkey| {
if (monkey.inspect_count > max[0] and monkey.inspect_count > max[1]) {
max[1] = max[0];
max[0] = monkey.inspect_count;
} else if (monkey.inspect_count > max[1]) {
max[1] = monkey.inspect_count;
}
monkey.items.deinit();
}
return max[0] * max[1];
}
fn parse(allocator: std.mem.Allocator, input: []const u8) []Monkey {
var monkeys = std.ArrayList(Monkey).init(allocator);
var monkey_iter = std.mem.split(u8, input, "\n\n");
while (monkey_iter.next()) |monkey_data| {
var monkey = std.mem.split(u8, monkey_data, "\n");
var line = monkey.next().?;
var id = std.fmt.parseInt(u8, line[7 .. line.len - 1], 0) catch unreachable;
var items = std.ArrayList(u64).init(allocator);
line = monkey.next().?;
var items_iter = std.mem.split(u8, line[18..], ", ");
while (items_iter.next()) |item| {
items.append(std.fmt.parseInt(u64, item, 0) catch unreachable) catch unreachable;
}
const operation = blk: {
line = monkey.next().?;
var op = Operation{ .symbol = line[23] };
if (line[25] != 'o') {
op.fixed = true;
op.fixed_number = std.fmt.parseInt(u8, line[25..], 0) catch unreachable;
}
break :blk op;
};
const throw_rules = blk: {
line = monkey.next().?;
const multiple_of = std.fmt.parseInt(u8, line[21..], 0) catch unreachable;
line = monkey.next().?;
const iftrue = std.fmt.parseInt(u8, line[29..], 0) catch unreachable;
line = monkey.next().?;
const iffalse = std.fmt.parseInt(u8, line[30..], 0) catch unreachable;
break :blk Monkey.Throw_rules{
.multiple_of = multiple_of,
.true = iftrue,
.false = iffalse,
};
};
monkeys.append(Monkey{
.id = id,
.items = items,
.operation = operation,
.throw_rules = throw_rules,
}) catch unreachable;
}
return monkeys.toOwnedSlice() catch unreachable;
}
pub fn puzzle_1(allocator: std.mem.Allocator, input: []const u8) Result {
var monkeys = parse(allocator, input);
defer allocator.free(monkeys);
var i: usize = 0;
while (i < 20) : (i += 1) {
for (monkeys) |*monkey| {
while (monkey.items.items.len > 0) {
const new_worry_level = monkey.inspect();
const throw_to = monkey.throws_to(new_worry_level / 3);
monkeys[throw_to].items.append(new_worry_level / 3) catch unreachable;
}
}
}
return .{ .int = @intCast(i32, answer(monkeys)) };
}
pub fn puzzle_2(allocator: std.mem.Allocator, input: []const u8) Result {
var monkeys = parse(allocator, input);
defer allocator.free(monkeys);
const mod = blk: {
var r: u64 = 1;
for (monkeys) |monkey| r *= monkey.throw_rules.multiple_of;
break :blk r;
};
var i: usize = 0;
while (i < 10000) : (i += 1) {
for (monkeys) |*monkey| {
while (monkey.items.items.len > 0) {
const new_worry_level = monkey.inspect();
const throw_to = monkey.throws_to(new_worry_level % mod);
monkeys[throw_to].items.append(new_worry_level % mod) catch unreachable;
}
}
}
return .{ .int = @intCast(i64, answer(monkeys)) };
}
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