王位继承顺序

/*
 * 思路：
 * 1. 与普通Java实现相同，但使用Stream API简化某些操作。
 * 2. 使用哈希表来存储家族关系，使用集合来记录死亡人员。
 * 3. 在获取继承顺序时，使用Stream过滤死亡人员。
 */
import java.util.*;
import java.util.stream.Collectors;

class ThroneInheritance {
    private String king;
    private Map<String, List<String>> family;
    private Set<String> dead;

    public ThroneInheritance(String kingName) {
        this.king = kingName;
        this.family = new HashMap<>();
        this.family.put(kingName, new ArrayList<>());
        this.dead = new HashSet<>();
    }

    public void birth(String parentName, String childName) {
        family.computeIfAbsent(parentName, k -> new ArrayList<>()).add(childName);
        family.put(childName, new ArrayList<>());
    }

    public void death(String name) {
        dead.add(name);
    }

    public List<String> getInheritanceOrder() {
        List<String> order = new ArrayList<>();
        getInheritanceOrderStream(king).forEach(order::add);
        return order;
    }

    private Stream<String> getInheritanceOrderStream(String person) {
        return Stream.concat(
            dead.contains(person) ? Stream.empty() : Stream.of(person),
            family.getOrDefault(person, Collections.emptyList())
                .stream()
                .flatMap(this::getInheritanceOrderStream)
        );
    }
}