leetcode 移除链表中的元素(递归方法)

朱雀 2023-06-25 06:01 121阅读 0赞

leetcode 203号题

[https://leetcode-cn.com/problems/remove-linked-list-elements/submissions/][https_leetcode-cn.com_problems_remove-linked-list-elements_submissions]

public class LinkedNode<E> {
    
        public E e;
        public LinkedNode<E> next;
    
        LinkedNode(E e) {
            this.e = e;
            this.next = null;
        }
    
        LinkedNode(E e, LinkedNode<E> next) {
            this.e = e;
            this.next = next;
        }
    }

/**
     * @description 删除列表中元素
     * @author: lierl
     * @date 2019/12/26 09:47
     * @version: 1.0
     **/
    public class LinkedListRemoveMain {
    
        private static LinkedNode<Integer> removeElement(LinkedNode<Integer> node, Integer e) {
            if(node == null) {
                return null;
            }
    
            if(node.e.equals(e)) {
                return removeElement(node.next, e);
            }
            node.next = removeElement(node.next, e);
            return node;
        }
    
    
    
        public static void main(String[] args) {
    
            Integer[] arr = {1,2,3,4,5,6,2,5,1};
            LinkedNode<Integer> head = new LinkedNode<>(arr[0]);
            LinkedNode<Integer> cur = head;
            for (int i=1; i < arr.length; i++) {
                LinkedNode<Integer> node = new LinkedNode<>(arr[i]);
                cur.next = node;
                cur = node;
            }
            printLinkedList(head);
            //删除元素为1
            LinkedNode<Integer> leftNode1 = removeElement(head, 1);
            printLinkedList(leftNode1);
            //删除元素为2
            LinkedNode<Integer> leftNode2 = removeElement(head, 2);
            printLinkedList(leftNode2);
    
    
    
    
        }
    
        private static void printLinkedList(LinkedNode<Integer> head) {
            StringBuilder builder = new StringBuilder();
            while(head != null) {
                builder.append(head.e + " --> ");
                head = head.next;
            }
            builder.append(" NULL");
    
            System.out.println(builder.toString());
        }
    }

执行结果：

1 --> 2 --> 3 --> 4 --> 5 --> 6 --> 2 --> 5 --> 1 -->  NULL
    2 --> 3 --> 4 --> 5 --> 6 --> 2 --> 5 -->  NULL
    1 --> 3 --> 4 --> 5 --> 6 --> 5 -->  NULL

[https_leetcode-cn.com_problems_remove-linked-list-elements_submissions]: https://leetcode-cn.com/problems/remove-linked-list-elements/submissions/