一、题目

二、代码

/** * Definition for singly-linked list. * struct ListNode { * int val; * ListNode *next; * ListNode() : val(0), next(nullptr) {} * ListNode(int x) : val(x), next(nullptr) {} * ListNode(int x, ListNode *next) : val(x), next(next) {} * }; */
class Solution {
    
public:
    ListNode* removeElements(ListNode* head, int val) {
    
            
    ///统一链表格式
    ListNode* dummyhead = new ListNode(0);  //设置虚假的头结点 为了使得单节点和多节点情况统一 
    dummyhead->next = head;

    //Define Action Nodes
    ListNode* process_node = new ListNode(0); 
    process_node=dummyhead;

    //定义临时节点
    ListNode* temp_node = new ListNode(0);   

    while(process_node->next!=nullptr)
    {
    
       if(process_node->next->val==val)     //If the next node value of the processing node is equal to val Then change the pointer directly
       {
    
          temp_node=process_node->next;
          process_node->next=temp_node->next;   
       }
       else
       {
    
         process_node=process_node->next;
       }

   }  
    std::cout<<"all is finish "<<std::endl; 
    delete temp_node;
   // delete process_node; //和dummyhead指向同一片空间 所以删不掉
    return dummyhead->next;

    }
};

三、运行结果