Given a sorted linked list, delete all nodes that have 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.

 

Code:

 

class Solution {public:    ListNode *deleteDuplicates(ListNode *head) {        if(head==NULL) return head;        ListNode *start=new ListNode(0);        start->next=head;        ListNode *pre=start;        ListNode *cur=head;        ListNode *nex=head->next;        bool detect=false;        while(nex){            if(nex->val==cur->val){                detect=true;                cur->next=nex->next;                delete nex;            }            else if(detect){                detect=false;                pre->next=cur->next;                delete cur;                cur=nex;            }            else{                pre=cur;                cur=nex;            }            nex=nex->next;        }        if(detect){            pre->next=NULL;            delete cur;        }        head=start->next;        delete start;        return head;    }};