c_cpp 203.删除链接列表元素

Posted 2021-05-14

//Runtime: 24 ms, faster than 99.22%

class Solution {
public:
    ListNode* removeElements(ListNode* head, int val) {
        if(head == nullptr) return nullptr;
        head->next = removeElements(head->next,val);
        return head->val == val ? head->next : head;
    }
};

//Runtime: 28 ms, faster than 92.69%

class Solution {
public:
    ListNode* removeElements(ListNode* head, int val) {
        if(head == nullptr) return nullptr;
        
        ListNode pseudo_head(0);
        pseudo_head.next = head;
        ListNode* prev = &pseudo_head;
        ListNode* cur = prev->next;
        while(cur){
            if(cur->val == val)
                prev->next = cur->next;
            else
                prev = prev->next;
            cur = cur->next;
        }
        return pseudo_head.next;
    }
};