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const std = @import("std");
const aoc = @import("aoc");
const Range = struct { min: u32, max: u32 };
const FieldRule = struct { name: []const u8, r1: Range, r2: Range };
fn assert(comptime T: type, part: ?T) !T {
if (part == null) return aoc.Error.InvalidInput;
return part.?;
}
fn parseRange(str: []const u8) !Range {
const sep = try assert(usize, std.mem.indexOfScalar(u8, str, '-'));
if (sep == str.len - 1) return aoc.Error.InvalidInput;
return Range{
.min = try std.fmt.parseInt(u32, str[0..sep], 10),
.max = try std.fmt.parseInt(u32, str[sep + 1 ..], 10),
};
}
fn parseRules(rules: *std.ArrayList(FieldRule), str: []const u8) !void {
var lineit = std.mem.tokenize(u8, str, "\n");
while (lineit.next()) |line| {
const sep = try assert(usize, std.mem.indexOf(u8, line, ": "));
if (sep == line.len - 1) return aoc.Error.InvalidInput;
const name = line[0..sep];
var rangepart = line[sep + 2 ..];
var spaceit = std.mem.tokenize(u8, rangepart, " ");
const r1 = try parseRange(try assert([]const u8, spaceit.next()));
_ = spaceit.next();
const r2 = try parseRange(try assert([]const u8, spaceit.next()));
try rules.append(FieldRule{ .name = name, .r1 = r1, .r2 = r2 });
}
}
fn parseVals(vals: *std.ArrayList(u32), str: []const u8) !void {
var lineit = std.mem.tokenize(u8, str, "\n");
while (lineit.next()) |line| {
var partit = std.mem.tokenize(u8, line, ",");
while (partit.next()) |part| {
try vals.append(try std.fmt.parseInt(u32, part, 10));
}
}
}
fn matchesRule(rule: FieldRule, v: u32) bool {
return (v >= rule.r1.min and v <= rule.r1.max or v >= rule.r2.min and v <= rule.r2.max);
}
fn hasRule(rules: []FieldRule, v: u32) bool {
for (rules) |r| {
if (matchesRule(r, v)) return true;
}
return false;
}
fn printCandidates(candidates: []u1, rulecount: usize, remove: usize) void {
var i: u32 = 0;
while (i < rulecount) : (i += 1) {
for (candidates[i * rulecount .. (i + 1) * rulecount]) |c| {
aoc.debugfmt("{} ", .{c});
}
if (i == remove) aoc.debugfmt(" <<<", .{});
aoc.debugfmt("\n", .{});
}
}
fn part1(allocator: std.mem.Allocator, input: []u8, args: [][]u8) !?[]u8 {
_ = args;
var answer: u32 = 0;
var rules = std.ArrayList(FieldRule).init(allocator);
defer rules.deinit();
var othervals = std.ArrayList(u32).init(allocator);
defer othervals.deinit();
var secit = std.mem.split(u8, input, "\n\n");
try parseRules(&rules, try assert([]const u8, secit.next()));
_ = secit.next();
try parseVals(&othervals, (try assert([]const u8, secit.next()))[16..]);
for (othervals.items) |v| {
if (!hasRule(rules.items, v)) answer += v;
}
return try std.fmt.allocPrint(allocator, "{}", .{answer});
}
fn part2(allocator: std.mem.Allocator, input: []u8, args: [][]u8) !?[]u8 {
_ = args;
var rules = std.ArrayList(FieldRule).init(allocator);
defer rules.deinit();
var ownvals = std.ArrayList(u32).init(allocator);
defer ownvals.deinit();
var othervals = std.ArrayList(u32).init(allocator);
defer othervals.deinit();
var secit = std.mem.split(u8, input, "\n\n");
try parseRules(&rules, try assert([]const u8, secit.next()));
try parseVals(&ownvals, (try assert([]const u8, secit.next()))[13..]);
try parseVals(&othervals, (try assert([]const u8, secit.next()))[16..]);
const rulecount = rules.items.len;
{
var index: u32 = 0;
while (index < othervals.items.len) {
var i: u32 = 0;
while (i < rulecount) : (i += 1) {
if (!hasRule(rules.items, othervals.items[index + i]))
break;
}
if (i == rulecount) {
index += @intCast(u32, rulecount);
} else {
if (aoc.debug)
aoc.debugfmt("REMOVE: ", .{});
i = 0;
while (i < rulecount) : (i += 1) {
if (aoc.debug)
aoc.debugfmt("{} ", .{othervals.items[index]});
_ = othervals.orderedRemove(index);
}
if (aoc.debug)
aoc.debugfmt("\n", .{});
}
}
}
var candidates = try allocator.alloc(u1, rulecount * rulecount);
defer allocator.free(candidates);
std.mem.set(u1, candidates, 1);
if (aoc.debug)
aoc.debugfmt("{}\n", .{othervals.items.len});
{
var index: u32 = 0;
while (index < othervals.items.len) : (index += 1) {
const ri = index % rulecount;
const v = othervals.items[index];
for (rules.items) |r, rri| {
if (!matchesRule(r, v)) {
candidates[ri * rulecount + rri] = 0;
}
}
}
}
var answer: u64 = 1;
{
var index: u32 = 0;
while (index < rulecount * rulecount) : (index += 1) {
var ri = index % rulecount;
const cc = candidates[ri * rulecount .. (ri + 1) * rulecount];
if (std.mem.count(u1, cc, ([_]u1{1})[0..]) == 1) {
const field = std.mem.indexOfScalar(u1, cc, 1).?;
if (std.mem.indexOf(u8, rules.items[field].name, "departure") != null)
answer *= ownvals.items[ri];
for (ownvals.items) |_, ii| {
candidates[ii * rulecount + field] = 0;
}
if (aoc.debug) {
printCandidates(candidates, rulecount, ri);
aoc.debugfmt("\n", .{});
}
}
}
}
return try std.fmt.allocPrint(allocator, "{}", .{answer});
}
pub const main = aoc.main(part1, part2, .{ "25972", "622670335901" });
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