Day 27.1.txt

83. Remove Duplicates from Sorted List

Given the head of a sorted linked list, delete all duplicates such that each element appears only once. Return the linked list sorted as well.

 

Example 1:


Input: head = [1,1,2]
Output: [1,2]
Example 2:


Input: head = [1,1,2,3,3]
Output: [1,2,3]
 

Constraints:

The number of nodes in the list is in the range [0, 300].
-100 <= Node.val <= 100
The list is guaranteed to be sorted in ascending order.


/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode() {}
 *     ListNode(int val) { this.val = val; }
 *     ListNode(int val, ListNode next) { this.val = val; this.next = next; }
 * }
 */
class Solution {
    public ListNode deleteDuplicates(ListNode head) {
        if(head==null)
            return null;
        if(head.next==null)
            return head;
        if(head.next.next==null&&head.val==head.next.val)
        {
            head.next=null;
            return head;
        }
        ListNode ptr,k;
        int f=0;
        for(ptr=head;ptr.next.next!=null;ptr=ptr.next)
        {
            if(ptr.val==ptr.next.val)
            {
                k=ptr;
                while(k.val==ptr.val&&k.next!=null)
                {
                    k=k.next;
                }
                ptr.next=k;
            }
            if(ptr.next.next==null)
            {
                f=1;
                break;
            }
        }
        if(ptr.val==ptr.next.val&&f==1)
            ptr.next=null;
        else if(ptr.val==ptr.next.val)
            ptr.next=null;
        return head;
    }
}