Leetcode 203. 删除链表中的节点

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
class Solution {
public:
    ListNode* removeElements(ListNode* head, int val) {
        ListNode* ans=head,*p;
        while(ans && ans->val==val) ans=head->next,delete head,head=ans;
        if(!ans) return ans;
        while(head->next)
            if(head->next->val!=val) head=head->next;
            else p=head->next,head->next=p->next,delete p;
        return ans;
    }
};