Remove all elements from a linked list of integers that have valueval.

Example

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

Return: 1 --> 2 --> 3 --> 4 --> 5

我的解法：

// Linklist.cpp : Defines the entry point for the console application.//#include "stdafx.h"#include
    
     using namespace std;  struct ListNode  {      int val;      ListNode *next;      ListNode(int x) : val(x), next(NULL) {}  };     ListNode* removeElements(ListNode* head, int val)     {        if(head == NULL)return head;                ListNode* pre = NULL;        ListNode* root = head;        ListNode* current = head;                        while(current!=NULL)        {                        if(current->val == val)            {                if(pre==NULL)                {					current = current->next;                    root = current;                                    }                else                {                    pre->next = current->next;                    current = current->next;                                    }                                           }            else            {                pre = current;                current =current->next;                                            }        }                return root;    }int _tmain(int argc, _TCHAR* argv[]){	ListNode* temp = new ListNode(2);	ListNode* temp_next = new ListNode(1);	temp->next = temp_next;	removeElements(temp,1);	return 0;}
    

python的解法：

class Solution:    # @param {ListNode} head    # @param {integer} val    # @return {ListNode}    def removeElements(self, head, val):        dummy = ListNode(-1)        dummy.next = head        prev = dummy        while head:            if head.val == val:                prev.next = head.next                head = prev            prev = head            head = head.next        return dummy.next

一个非常简洁的解法：

struct ListNode* removeElements(struct ListNode* head, int val) {    if (head&&head->val==val)head=removeElements(head->next, val);    if (head&&head->next)head->next=removeElements(head->next, val);    return head;}