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const std = @import("std");
const print = std.debug.print;
const assert = std.debug.assert;
const ArrayList = std.ArrayList;
const HashMap = std.HashMap;
const mem = std.mem;
const fin = mem.trim(u8, @embedFile("./input.txt"), &std.ascii.whitespace);
var gpa = std.heap.GeneralPurposeAllocator(.{}){};
const allocator = gpa.allocator();
const Condition = struct {
let: u64,
islt: bool,
thresh: u64,
pub fn check(self: @This(), val: u64) bool {
return if (self.islt) val < self.thresh else val > self.thresh;
}
};
const Rule = struct {
cond: ?Condition,
res: []const u8,
fn parseCondition(s: []const u8) Condition {
var splitCond = mem.tokenizeAny(u8, s, "<>");
const let: u64 = switch (splitCond.next().?[0]) {
'x' => 0,
'm' => 1,
'a' => 2,
's' => 3,
else => unreachable,
};
const islt = mem.count(u8, s, "<") != 0;
const thresh = std.fmt.parseInt(u64, splitCond.next().?, 10) catch unreachable;
return Condition{
.let = let,
.islt = islt,
.thresh = thresh,
};
}
pub fn parse(s: []const u8) Rule {
var splitRule = mem.tokenizeScalar(u8, s, ':');
const first = splitRule.next().?;
const second = splitRule.next();
return if (second) |resStr|
Rule{
.cond = parseCondition(first),
.res = resStr,
}
else
Rule{
.cond = null,
.res = first,
};
}
pub fn check(self: @This(), ratings: Ratings) ?[]const u8 {
if (self.cond) |cond| {
return if (cond.check(ratings[cond.let])) self.res else null;
}
return self.res;
}
pub fn getNext(list: RuleList, ratings: Ratings) []const u8 {
for (list) |rule| {
const res = rule.check(ratings) orelse continue;
return res;
}
unreachable;
}
pub fn rangeCombs(rules: RuleGraph, curr: []const u8, ranges: Ranges) u64 {
if (mem.eql(u8, curr, "A")) {
var res: u64 = 1;
for (ranges) |r| {
res *= r[1] - r[0] + 1;
}
return res;
} else if (mem.eql(u8, curr, "R")) {
return 0;
}
var ans: u64 = 0;
var ranges_rej: Ranges = undefined;
@memcpy(&ranges_rej, &ranges);
const rule_list = rules.get(curr).?;
for (rule_list) |rule| {
if (rule.cond) |cond| {
const thresh = cond.thresh;
const l = ranges[cond.let][0];
const r = ranges[cond.let][1];
var ranges_suc: Ranges = undefined;
@memcpy(&ranges_suc, &ranges_rej);
if (cond.islt) {
ranges_suc[cond.let] = nextRange(
ranges_suc[cond.let],
.{ l, thresh - 1 },
);
ranges_rej[cond.let] = nextRange(
ranges_rej[cond.let],
.{ thresh, r },
);
} else {
ranges_suc[cond.let] = nextRange(
ranges_suc[cond.let],
.{ thresh + 1, r },
);
ranges_rej[cond.let] = nextRange(
ranges_rej[cond.let],
.{ l, thresh },
);
}
ans += rangeCombs(rules, rule.res, ranges_suc);
} else {
ans += rangeCombs(rules, rule.res, ranges_rej);
}
}
return ans;
}
};
const Range = [2]u64;
const Ranges = [4]Range;
const Ratings = []u64;
const RuleList = []const Rule;
const RuleGraph = std.StringHashMap(RuleList);
fn nextRange(lhs: Range, rhs: Range) Range {
return Range{
@max(lhs[0], rhs[0]),
@min(lhs[1], rhs[1]),
};
}
pub fn solve(rules: RuleGraph, parts: []const Ratings) !void {
var part1: u64 = 0;
for (parts) |ratings| {
var curr: []const u8 = "in";
const accepted = while (true) {
if (mem.eql(u8, curr, "A")) {
break true;
} else if (mem.eql(u8, curr, "R")) {
break false;
}
curr = Rule.getNext(rules.get(curr).?, ratings);
};
if (accepted) {
for (ratings) |r| {
part1 += r;
}
}
}
print("{d}\n", .{part1});
const ranges = [_]Range{Range{ 1, 4000 }} ** 4;
const ans = Rule.rangeCombs(rules, "in", ranges);
print("{d}\n", .{ans});
}
pub fn main() !void {
var segments = mem.tokenizeSequence(u8, fin, "\n\n");
var splitRules = mem.tokenizeScalar(u8, segments.next().?, '\n');
var splitWorkflows = mem.tokenizeScalar(u8, segments.next().?, '\n');
var allRules = RuleGraph.init(allocator);
var parts = ArrayList(Ratings).init(allocator);
while (splitRules.next()) |line| {
var list = mem.tokenizeAny(u8, line, "{},");
const id = list.next().?;
var rules = ArrayList(Rule).init(allocator);
while (list.next()) |ruleStr| {
try rules.append(Rule.parse(ruleStr));
}
try allRules.put(id, rules.items);
}
while (splitWorkflows.next()) |line| {
var splitRatings = mem.tokenizeAny(u8, line, "{=,xmas}");
var ratings = ArrayList(u64).init(allocator);
while (splitRatings.next()) |r| {
try ratings.append(try std.fmt.parseInt(u64, r, 10));
}
try parts.append(ratings.items);
}
try solve(allRules, parts.items);
}
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