从有向图字典构建组

Question

给定一个表示嵌套组及其成员的有向图字典，返回给定组的所有用户。

例子-

Hashmap-

key|Values

Group1- [ Group3, Group5, User8, User2]
Group2 -[ Group1, User9]
Group3 -[ Group4, User5]
Group4 -[ User1, User3]
Group5 -[ User4, User7]

O/P 应该是：

group1 : [User1, User3,User5, User4, User7,User8, User2]
group2 : [User1, User3,User5, User6, User7,User8, User9]
group3: [User1, User3,User5]
group4: [User1, User3]
group5: [User4, User7]

我已经尝试过各种方式，例如递归函数，但我只是摸不着头脑。

public static void main(String[] args) {
        HashMap<String, List<String>> hmap = new HashMap<String,List<String>>();
        List<String> l1 = new ArrayList<String>();
        List<String> l2 = new ArrayList<String>();
        List<String> l3 = new ArrayList<String>();
        List<String> l4 = new ArrayList<String>();
        List<String> l5 = new ArrayList<String>();
        l1.add("group3"); l1.add("group5"); l1.add("user8"); l1.add("user2");
        l2.add("group1"); l2.add("user9");
        l3.add("group4"); l3.add("user5");
        l4.add("user1"); l4.add("user3");
        l5.add("user4"); l5.add("user9");
        hmap.put("group1",l1);
        hmap.put("group2",l2);
        hmap.put("group3",l3);
        hmap.put("group4",l4);
        System.out.println(hmap);
        flatten(hmap);

    }


    public static void flatten(HashMap<String, List<String>> hmap){
        ArrayList<String> groups = new ArrayList<String>();
        for(Entry<String,List<String>> entryset : hmap.entrySet()){
            groups.add(entryset.getKey());
        }
        System.out.println(groups);
        for(Entry<String,List<String>> entryset : hmap.entrySet()){
            String s1 = entryset.getKey();
            //HashSet<String> set1 = new HashSet<String>();
            ArrayList<String> values = new ArrayList<String>();
            values.addAll(entryset.getValue());

        }

Answer 1

这是使用 Scala 的一种方法：

def run(): Unit =
{
    /* Simply initializing the given data into User and Group classes */
    val (u1, u2, u3, u4) = (new User("u1"), new User("u2"), new User("u3"), new User("u4"))
    val (u5, u6, u7, u8, u9) = (new User("u5"), new User("u6"), new User("u7"), new User("u8"), new User("u9"))
    val g5 = new Group(List(u4, u7))
    val g4 = new Group(List(u1, u3))
    val g3 = new Group(List(g4, u5))
    val g1 = new Group(List(g3, g5, u8, u2))
    val g2 = new Group(List(g1, u9))

    /* Put the groups into a list */
    var groups = List(g1, g2, g3, g4, g5)

    /* Map/loop over each group, calling `resolveItems` on each */
    groups = groups.map{_.resolveItems}

    /* Print out each of the resolved groups */
    groups.foreach{println}
}

/* A simple class representing the Group entity */
case class Group(var items: List[Any])
{
    /* 
        Returns a new group by recursively resolving the items
        in this group into only users
    */
    def resolveItems: Group =
    {
        new Group(this.items.map{
            // If the item is a group, resolve it into users
            case g: Group => g.resolveItems
            // If the item is a user, just move along
            case u: User => u
        }.distinct)
    }

    /* Override to string for pretty printing */
    override
    def toString: String = items.mkString(", ")
}

/* Simply class representing the user entity */
case class User(val name: String)
{
    override
    def toString : String = name
}

输出：

u1, u3, u5, u4, u7, u8, u2
u1, u3, u5, u4, u7, u8, u2, u9
u1, u3, u5
u1, u3
u4, u7