Remove Duplicates from Sorted List II
/** * 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) { if(head ==NULL) return head; if(head->next ==NULL) return head; ListNode *res = head; int head_val; while(head){ head_val = head->val; if(head->next && head ->next->val == head_val){ while(head && head->val == head_val) //去掉开头重复的 { head =head->next; } } else break; } res=head; //如果重复的部分不是在开头,需要记录pre结点。这里特别要注意逻辑性,head只有在后续结点不是重复结点的情况下,才可以往后移动 while(head){ if(head->next == NULL) break; ListNode* p_i = head->next; int next_val = p_i->val; if(p_i!=NULL &&p_i->next!=NULL && p_i->next->val == next_val){ while(p_i && p_i->val ==next_val) { p_i =p_i->next; } if(p_i == NULL) {head->next=NULL;break;} head->next = p_i; } else head = p_i; } return res; } };