adventofcode/src/main/java/AoC2020_16.java at main · pareronia/adventofcode · GitHub

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import static java.util.stream.Collectors.toList;

import static java.util.stream.Collectors.toSet;

import java.util.Arrays;

import java.util.HashMap;

import java.util.HashSet;

import java.util.List;

import java.util.Map;

import java.util.Map.Entry;

import java.util.Set;

import java.util.function.Predicate;

import java.util.stream.IntStream;

import java.util.stream.Stream;

import com.github.pareronia.aoc.RangeInclusive;

import com.github.pareronia.aoc.StringOps;

import com.github.pareronia.aoc.solution.Sample;

import com.github.pareronia.aoc.solution.Samples;

import com.github.pareronia.aoc.solution.SolutionBase;

public class AoC2020_16

extends SolutionBase<AoC2020_16.Notes, Integer, Long> {

private AoC2020_16(final boolean debug) {

super(debug);

}

public static AoC2020_16 create() {

return new AoC2020_16(false);

}

public static AoC2020_16 createDebug() {

return new AoC2020_16(true);

}

@Override

protected AoC2020_16.Notes parseInput(final List<String> inputs) {

return Notes.fromInput(inputs);

}

@Override

public Integer solvePart1(final Notes notes) {

return notes.tickets.stream()

.flatMap(t -> t.invalidValues(notes.rules).stream())

.mapToInt(Integer::valueOf)

.sum();

}

@Override

public Long solvePart2(final Notes notes) {

return Matches.create(notes.tickets, notes.rules).stream()

.filter(m -> m.rule.field.startsWith("departure "))

.mapToLong(m -> notes.myTicket.values.get(m.idx))

.reduce(1, (a, b) -> a * b);

}

@Samples({

@Sample(method = "part1", input = TEST1, expected = "71"),

@Sample(method = "part2", input = TEST2, expected = "1716"),

})

public static void main(final String[] args) throws Exception {

AoC2020_16.create().run();

}

private static final String TEST1 = """

class: 1-3 or 5-7

row: 6-11 or 33-44

seat: 13-40 or 45-50

your ticket:

7,1,14

nearby tickets:

7,3,47

40,4,50

55,2,20

38,6,12

""";

private static final String TEST2 = """

departure date: 0-1 or 4-19

departure time: 0-5 or 8-19

departure track: 0-13 or 16-19

your ticket:

11,12,13

nearby tickets:

3,9,18

15,1,5

5,14,9

""";

private record Rule(

String field,

Set<RangeInclusive<Integer>> validRanges

) {

public static Rule parseRule(final String s) {

final var splits1 = s.split(": ");

final var builder = Rule.builder();

builder.field(splits1[0]);

for (final var split : splits1[1].split(" or ")) {

final var splits3 = split.split("-");

final int start = Integer.parseInt(splits3[0]);

final int end = Integer.parseInt(splits3[1]);

builder.validRange(RangeInclusive.between(start, end));

}

return builder.build();

}

public boolean validate(final int value) {

return this.validRanges.stream().anyMatch(r -> r.contains(value));

}

public static RuleBuilder builder() {

return new RuleBuilder();

}

private static final class RuleBuilder {

private String field;

private final Set<RangeInclusive<Integer>> validRanges = new HashSet<>();

public Rule build() {

return new Rule(this.field, this.validRanges);

}

public RuleBuilder field(final String field) {

this.field = field;

return this;

}

public RuleBuilder validRange(final RangeInclusive<Integer> validRange) {

this.validRanges.add(validRange);

return this;

}

private record Ticket(List<Integer> values) {

public static Ticket parseTicket(final String s) {

return new Ticket(Arrays.stream(s.split(","))

.map(Integer::parseInt)

.collect(toList()));

}

public boolean invalid(final Set<Rule> rules) {

return this.values.stream()

.anyMatch(fieldDoesNotMatchAnyRule(rules));

}

public List<Integer> invalidValues(final Set<Rule> rules) {

return this.values.stream()

.filter(fieldDoesNotMatchAnyRule(rules))

.collect(toList());

}

private Predicate<Integer> fieldDoesNotMatchAnyRule(final Set<Rule> rules) {

return v -> rules.stream().noneMatch(r -> r.validate(v));

}

record Notes(

Set<Rule> rules, Ticket myTicket, List<Ticket> tickets) {

public static Notes fromInput(final List<String> input) {

final List<List<String>> blocks = StringOps.toBlocks(input);

final Set<Rule> rules = blocks.get(0).stream()

.map(Rule::parseRule)

.collect(toSet());

final Ticket myTicket = Ticket.parseTicket(blocks.get(1).get(1));

final List<Ticket> tickets = blocks.get(2).stream().skip(1)

.map(Ticket::parseTicket)

.collect(toList());

return new Notes(rules, myTicket, tickets);

}

private static final record Match(Rule rule, int idx) { }

private static final record Matches(Map<Rule, Set<Integer>> matches) {

private static boolean matchColumn(final List<Ticket> tickets,

final int column, final Rule rule) {

return tickets.stream()

.map(t -> t.values.get(column))

.allMatch(rule::validate);

}

public static Matches create(

final List<Ticket> tickets,

final Set<Rule> rules

) {

final List<Ticket> validTickets = tickets.stream()

.filter(t -> !t.invalid(rules))

.collect(toList());

final Set<Integer> idxs = IntStream

.range(0, validTickets.get(0).values.size())

.boxed()

.collect(toSet());

final Map<Rule, Set<Integer>> matches = new HashMap<>();

for (final Rule rule : rules) {

matches.put(rule, new HashSet<>());

}

for (final Rule rule : rules) {

for (final Integer idx : idxs) {

if (matchColumn(validTickets, idx, rule)) {

matches.get(rule).add(idx);

}

return new Matches(matches);

}

private void remove(final Match match) {

this.matches.remove(match.rule);

this.matches.values().stream()

.forEach(v -> v.remove(match.idx));

}

private Match next() {

final Rule rule = this.matches.entrySet().stream()

.filter(e -> e.getValue().size() == 1)

.map(Entry::getKey)

.findFirst().orElseThrow();

final Integer idx = matches.get(rule).iterator().next();

return new Match(rule, idx);

}

public Stream<Match> stream() {

final Stream.Builder<Match> builder = Stream.builder();

while (!this.matches.isEmpty()) {

final Match nextMatch = next();

builder.add(nextMatch);

remove(nextMatch);

}

return builder.build();

}

adventofcode/src/main/java/AoC2020_16.java at main · pareronia/adventofcode · GitHub

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