Palindrome Linked List

class Solution {

public:

bool isPalindrome(ListNode* head) {

if(NULL==head||NULL==head->next) return 1;

int len=0;

stack<ListNode*>s;

ListNode *temp,*p=head;

while(p)

{

p=p->next;

len++;

}

ListNode* head1=head;

int i=1;

s.push(head1);

while(i<len/2)

{

head1=head1->next;

s.push(head1);

i++;

}

if(len%2==0) //必须判断奇偶；

{

head1=head1->next;

}

else{

head1=head1->next->next;

}

while(!s.empty())

{

temp=s.top();

s.pop();

if(temp->val==head1->val)

head1=head1->next;

else return 0;

}

return 1;

}

};

这个找中点有点慢，如果用双指针的话，fast=fast->next->next; slow=slow->next->next; 更快