复制单链表

Question

[3，5，4，2，1]我需要删除靠近尾部的节点，这应该像[1，2，3，5，4]有什么建议吗？

public void delete() {
    for(Node<T> current = getHead(); current != null; current = current.getNext()){
                System.out.println(temp.getValue());
                removeValue(temp.getValue());
            }
        }
    }
}

Answer 1

您根本不需要删除任何内容（我的意思是不需要调用removeValue）。只需将您遇到的值存储在一个集合中，如果该值已经在集合中，则相应地重新链接您的列表。如果你没有使用库代码的权利，用二进制搜索树来实现你的集合，这将是简单而高效的。

假设我有Set:的实现，我会这样做

public void makeUnique() {
    Set<T>  set      = new MySet<>();
    Node<T> current  = getHead();
    Node<T> previous = null;
    while (current != null) {
        // if current.getValue() is already in the set, we skip this node
        // (the add method of a set returns true iff the element was not 
        // already in the set and if not, adds it to the set)
        if (set.add(current.getValue()) { 
            // previous represents the last node that was actually inserted in the set.
            // All duplicate values encountered since then have been ignored so 
            // previous.setNext(current) re-links the list, removing those duplicates
            if (previous != null) {
                previous.setNext(current); 
                current.setPrevious(previous);
             }
            previous = current;
        }
        current = current.getNext();
    }
}