Question

如何修复代码（SinglyLinkedList类），以便remove方法有效？我尝试在索引0处删除，但不删除“USA”，而是删除索引2处的“Portugal”。当我尝试在索引1处删除时，它确实可以正常工作。任何帮助表示赞赏。

class SinglyLinkedList<E> { //---------------- nested Node class
    private static class Node<E> {
        private E element;
        private Node<E> next;

        public Node(E e, Node<E> n) {
            element = e;
            next = n;
        }

        public E getElement() {
            return element;
        }

        public Node<E> getNext() {
            return next;
        }

        public void setNext(Node<E> n) {
            next = n;
        }
    }

    private Node<E> head = null;
    private Node<E> tail = null;
    private int size = 0;

    public SinglyLinkedList() {
    }

    public int size() {
        return size;
    }

    public boolean isEmpty() {
        return size == 0;
    }

    public E first() {
        if (isEmpty()) return null;
        return head.getElement();
    }

    public E last() {
        if (isEmpty()) return null;
        return tail.getElement();
    }
    // update methods

    public void addFirst(E e) {
        head = new Node<>(e, head);
        if (size == 0)
            tail = head;
        size++;
    }

    public void addLast(E e) {
        Node<E> newest = new Node<>(e, null);
        if (isEmpty())
            head = newest;
        else
            tail.next = newest;
        tail = newest;
        size++;
    }

    public void printLinkedList() {
        Node<E> temp = head;
        for (int i = 0; i < size; i++) {
            System.out.println(temp.getElement());
            temp = temp.next;
        }
    }

    public void remove(int index) {
        //Node<E> newest = new Node(e, null);
        Node<E> current = head;
        for (int i = 0; i < index - 1; i++) {
            current = current.next;
            current = current.getNext();
        }
        current.next = current.next.next;
        size--;
    }

    public void add(int index, E e) {
        Node<E> newNode = new Node<>(e, null);
        if (index == 0) {
            newNode.next = head;
            head = newNode;
        } else {
            Node<E> current = head;
            for (int i = 1; i < index; i++) {
                current = current.next;
            }
            Node<E> tmp = current.next;
            current.next = newNode;
            newNode.next = tmp;
        }
        size++;
    }
}

public class SinglyLinkedListTest {
    public static void main(String args[]) {
        SinglyLinkedList<String> list = new SinglyLinkedList();

        list.addLast("USA");
        list.addLast("America");
        list.addLast("portugal");
        System.out.println(" ");
        list.printLinkedList();
        list.remove(0);
        System.out.println(" ");
        list.printLinkedList();
        list.removeLast();
        System.out.println(" ");
        list.printLinkedList();
        list.add(2, "hello");
        System.out.println(" ");
        list.printLinkedList();
    }
}

Answer 1

删除头部时，需要重新分配列表的head属性。一个简单的解决方案是添加条件来处理这种特殊情况：

public void remove(int index) {
  size--;

  if (index == 0) {
    head = head.next;
    return;
  }

  Node<E> current = head;
  for (int i = 0; i < index - 1; i++) {
    current = current.next;
  }
  current.next = current.next.next;
}

请注意，我从原始代码中删除了current = current.getNext();，在current = current.next;之后因为这是一个错误，跳过每一个元素。

我如何修复我的代码（SinglyLinkedList类），以便删除方法删除正确的索引？

1 个答案: