/**
* Definition for singly-linked list.
* struct ListNode {
* int val;
* ListNode *next;
* ListNode(int x) : val(x), next(NULL) {}
* };
*/
ListNode* reverse(ListNode* head) {
if(head == nullptr)
return nullptr;
ListNode* pre = nullptr;
ListNode* cur = head;
ListNode* next = head->next;
while(cur){
cur->next = pre;
pre = cur;
cur = next;
if(next)
next = next->next;
}
return pre;
}
class Solution {
public:
bool isPalindrome(ListNode* head) {
ListNode* fast = head;
ListNode* slow = head;
while(fast&&fast->next){
fast = fast->next->next;
slow = slow->next;
}
ListNode* re = reverse(slow);
while(head&&re){
if(head->val!=re->val){
return false;
}
head = head->next;
re = re->next;
}
return true;
}
};.
