有个错误就是member access within null pointer of type 'struct ListNode'  

其实就是判断了指针是否异常了，比如NULL->next之类。要记得用new给节点初始化，而指针不需要初始化

 

/** * 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;        ListNode* bighead = new ListNode(0);        ListNode* pre;        ListNode* move;                bighead->next = head;        pre = bighead;        move = head;                while(move != NULL && move->next != NULL){            if(move->next->val == move->val){                while((move->next != NULL) && (move->next->val == move->val)){                    move = move->next;                                    }                pre->next = move->next;                move = move->next;            }            else{                pre = pre->next;                move = move->next;            }        }        return bighead->next;    }};