leetcode 203——移除链表元素

leetcode 203——移除链表元素

题目描述：

删除链表中等于给定值 val 的所有节点。

示例:

输入: 1->2->6->3->4->5->6, val = 6
输出: 1->2->3->4->5

提交：

/**
 * 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) 
    {
        if(!head) return head;
        while(head->val == val)
        {
            ListNode* nextNode = head->next;
            delete head;
            head = nextNode; 
            if(!head) return head;
        }
        if(head)
        {
            ListNode* frontPosNode = head;
            ListNode* posNode = head->next;
            while(posNode)
            {
                if(posNode->val == val)
                {
                    ListNode* nextNode = posNode->next;
                    frontPosNode->next = posNode->next;
                    delete posNode;
                    posNode = nextNode; 
                }
                else
                {
                    frontPosNode = posNode;
                    posNode = posNode->next;
                }
            }    
        }

        return head;
    }
};