zoukankan      html  css  js  c++  java
  • [Leetcode 5] 83 Remove Duplicates from Sorted List

    Problem:

    Given a sorted linked list, delete all duplicates such that each element appear only once.

    For example,
    Given 1->1->2, return 1->2.
    Given 1->1->2->3->3, return 1->2->3.

    Analysis:

    It's similar to the remove duplicates from sorted array problem. Use pointers ptrA and ptrB. ptrA always points to the last position of non-duplicated list and ptrB go through the list. One important thing is that we need a third point always points to the previous position of ptrB to delete duplicates. The third pointer can ensure that those duplicated nodes have no reference point to them and thus can be GC cleaned as soon as possible.

    The time complexity is O(n) and the space complexity is O(n)

    Code:

    /**
     * Definition for singly-linked list.
     * public class ListNode {
     *     int val;
     *     ListNode next;
     *     ListNode(int x) {
     *         val = x;
     *         next = null;
     *     }
     * }
     */
    public class Solution {
        public ListNode deleteDuplicates(ListNode head) {
            // Start typing your Java solution below
            // DO NOT write main() function
            if (head == null) return null;
            
            ListNode cur=head, valid=head, prev=null;
            
            while (cur.next != null) {
                prev = cur;
                cur = cur.next;
                if (cur.val != valid.val) {
                    if (prev.val == valid.val) prev.next=null;
                    valid.next = cur;
                    valid = cur;
                } else {
                  prev.next = null;
                }
            }
            
            return head;
        }
    }

    Attention:

    To access Java field, use . not ->

  • 相关阅读:
    OAuth2.0协议流程
    记多个微服务同时被kill分析
    记一次调用API遇到的问题
    win10安装mysql遇到的坑
    nagios
    rmp安装mysql5.6
    桥接模式-xshell连接虚拟机
    VMWare虚拟机-网络适配器
    ***时间目录***
    docker常用命令
  • 原文地址:https://www.cnblogs.com/freeneng/p/3003323.html
Copyright © 2011-2022 走看看