Palindrome Linked List 判断链表是否回文 栈实现

Palindrome Linked List

 

Given a singly linked list, determine if it is a palindrome.

Follow up:
Could you do it in O(n) time and O(1) space?

/** * Definition for singly-linked list. * struct ListNode { *     int val; *     ListNode *next; *     ListNode(int x) : val(x), next(NULL) {} * }; */class Solution {public://判断链表是否是回文：逆转比较，入栈比较；    bool isPalindrome(ListNode* head) {                stack<ListNode *> s;        if(head==NULL)            return true;        ListNode *p=head;        while(p!=NULL)        {            s.push(p);            p=p->next;        }                bool f=true;        p=head;        while(!s.empty())        {            ListNode *tmp=s.top();            if(p->val!=tmp->val)            {                f=false;                break;            }            s.pop();            p=p->next;        }        return f;    }};