Remove Duplicates from Sorted List

题目

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.

思路

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
class Solution {
public:
    ListNode *deleteDuplicates(ListNode *head) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        if(!head)
            return head;
        ListNode *pre = head;
        ListNode *cur = head->next;
        while(cur)
        {
            if(cur->val!=pre->val)
            {
                pre = pre->next;
            }
            else
            {
                pre->next = cur->next;
            }
            cur = cur->next;
        }
        return head;
        
    }
};

 最新 java

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) { val = x; }
 * }
 */
public class Solution {
    public ListNode deleteDuplicates(ListNode head) {
        if(head == null) {
            return null;
        }
        ListNode pre = head;
        ListNode cur = head.next;
        while(cur != null) {
            if(cur.val != pre.val){
                pre.next = cur;
                pre = pre.next;
            }
            cur = cur.next;
        }
        pre.next = null;
        return head;
    }
}