玩转数据结构：第5章 链表和递归

Posted 2021-03-08 marlonkang

链表和递归

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5-1 Leetcode中和链表相关的问题 

Java类的递归，包含的成员变量有该类本身。

ListNode

//Definition for singly-linked list.
public class ListNode {

    public int val;
    public ListNode next;

    public ListNode(int x) {
        val = x;
    }
}

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/// Leetcode 203. Remove Linked List Elements
/// https://leetcode.com/problems/remove-linked-list-elements/description/

 Solution

/// Leetcode 203. Remove Linked List Elements
/// https://leetcode.com/problems/remove-linked-list-elements/description/

class Solution {

    public ListNode removeElements(ListNode head, int val) {

        while(head != null && head.val == val){
            ListNode delNode = head;
            head = head.next;
            delNode.next = null;
        }

        if(head == null)
            return head;

        ListNode prev = head;
        while(prev.next != null){
            if(prev.next.val == val) {
                ListNode delNode = prev.next;
                prev.next = delNode.next;
                delNode.next = null;
            }
            else
                prev = prev.next;
        }

        return head;
    }
}

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