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:
[0, 300].-100 <= Node.val <= 100
class Solution {
public ListNode deleteDuplicates(ListNode head) {
if(head == null || head.next == null){
return head ;
}
ListNode dummy = new ListNode(head.val);
ListNode ans = dummy ;
ListNode ptr = head.next ;
while(ptr!=null){
if(ptr.val!=dummy.val){
// ListNode temp = new ListNode(ptr.val);
dummy.next = ptr ;
dummy = dummy.next;
}
ptr = ptr.next;
}
dummy.next = null; //extra line of new approach
return ans ;
}
}
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