23
04/2015
[LeetCode] Remove Linked List Elements
Remove Linked List Elements
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
Credits:
Special thanks to @mithmatt for adding this problem and creating all test cases.
解题思路：
这道题挺简单的，注意队首为val值的情况即可。
/**
* 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* p=NULL, *q=NULL;
while(head!=NULL&&head->val==val){ //对于队首的情况
p=head;
head=head->next;
delete p;
}
p=head;
while(p!=NULL&&p->next!=NULL){
if(p->next->val==val){
q=p->next;
p->next=q->next;
delete q;
}else{
p=p->next;
}
}
return head;
}
};为简化代码，建立一个伪头结点，其next指向head，这样所有的操作都是一样，能够简化代码。
/**
* 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* myHead=new ListNode(0);
myHead->next=head;
ListNode* p=myHead, *q=NULL;
while(p->next!=NULL){
if(p->next->val==val){
q=p->next;
p->next=q->next;
delete q;
}else{
p=p->next;
}
}
head=myHead->next;
delete myHead;
return head;
}
};
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