【leetcode】203. Remove Linked List Elements
问题描述:
Remove all elements from a linked list of integers that have value val.
Example
Given: 1 --> 2 --> 6 --> 3 --> 4 --> 5 --> 6, val = 6
Return: 1 --> 2 --> 3 --> 4 --> 5
/**
* 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) {
}
};
翻译:
将单向链表中与所给val值相等的元素去掉。
例如:
所给输入值:1 --> 2 --> 6 --> 3 --> 4 --> 5 --> 6, val = 6
返回值:1 --> 2 --> 3 --> 4 --> 5
解题思路:
分情况考虑,首先判断是否为空链表,若非空再判断此链表第一个元素是否需要被第二个替换掉,然后判断链表的下一个元素是否需要被替换掉,接下来就递归调用,对之后的节点重复的进行同样的判断。
/**
* 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* temp;
temp = head;
if(!temp) return head;
else
{
if(temp -> val != val)
{
head = temp;
if(!temp -> next) return head;
else if(temp -> next -> val == val)
{
head -> next = temp -> next -> next;
head -> next = removeElements(head -> next, val);
}
else head -> next = removeElements(head -> next, val);
}
else if(temp -> val == val)
{
head = temp -> next;
head = removeElements(head, val);
}
}
return head;
}
};