Leetcode:remove duplicates from Sorted List II problem Solving report

Remove duplicates from Sorted List II

Given a sorted linked list, delete all nodes that has duplicate numbers, leaving only distinct numbers from the Original list.

For example,
Given 1->2->3->3->4->4->5 , return 1->2->5 .
Given 1->1->1->2->3 , return 2->3 .

Solution 1:

Use a del tag to delete the last duplicate character.

1 /**2 * Definition for singly-linked list.3 * public class ListNode {4 * int val;5 * ListNode Next;6 * ListNode (int x) {7 * val = x;8 * next = null;9  *     }Ten  * } One  */ A  Public classSolution { -      PublicListNode deleteduplicates (ListNode head) { -         if(Head = =NULL) { the             return NULL; -         } -          -         //record the head. +ListNode dummy =NewListNode (0); -Dummy.next =head; +          AListNode cur =dummy; at          -         //To delete the last node in the list of duplications. -         Booleandel =false; -          -          while(cur! =NULL) { -             if(Cur.next! =NULL in&& Cur.next.next! =NULL -&& Cur.next.val = =cur.next.next.val) { toCur.next =Cur.next.next; +del =true; -}Else { the                 if(del) { *Cur.next =Cur.next.next; $del =false;Panax Notoginseng}Else { -Cur =Cur.next; the                 } +             } A         } the          +         returnDummy.next; -     } $}

View CodeSolution 2:

Use a pre, a cur to scan, and when you encounter duplicates, use the For loop to skip all duplicate elements with cur.

1 /**2 * Definition for singly-linked list.3 * public class ListNode {4 * int val;5 * ListNode Next;6 * ListNode (int x) {7 * val = x;8 * next = null;9  *     }Ten  * } One  */ A  Public classSolution { -      PublicListNode deleteduplicates (ListNode head) { -         if(Head = =NULL) { the             return NULL; -         } -          -ListNode dummy =NewListNode (0); +Dummy.next =head; -          +ListNode pre =dummy; AListNode cur =Pre.next; at          -          while(cur! =NULL&& Cur.next! =NULL) { -             if(Cur.val = =cur.next.val) { -                  while(cur! =NULL&& Cur.val = =pre.next.val) { -Cur =Cur.next; -                 } in                  -                 //Delete all the duplication. toPre.next =cur; +}Else { -Cur =Cur.next; thePre =Pre.next; *             } $         }Panax Notoginseng          -         returnDummy.next; the     } +}

View Code

Leetcode:remove duplicates from Sorted List II problem Solving report