题解 | #判断一个链表是否为回文结构#

一、利用双指针

 * struct ListNode {
 *	int val;
 *	struct ListNode *next;
 * };
 */

class Solution {
public:
    /**
     * 
     * @param head ListNode类 the head
     * @return bool布尔型
     */
    bool isPail(ListNode* head) {
        // write code here
        vector<int> nums;
        while(head != NULL){
            nums.push_back(head->val);
            head = head->next;
        }
        int left = 0;
        int right = nums.size()-1;
        while(left <= right){
            if(nums[left] != nums[right])
            {
                return false;
            }
            left++;
            right--;
        }
        return true;
    }
};
> 



**二、栈**

``` /**
 * struct ListNode {
 *	int val;
 *	struct ListNode *next;
 * };
 */

class Solution {
public:
    /**
     * 
     * @param head ListNode类 the head
     * @return bool布尔型
     */
    bool isPail(ListNode* head) {
        // write code here
        ListNode* p = head;
        stack<int> s;
        
        while(p){
            s.push(p->val);
            p = p->next;
        }
        p = head;
        while(!s.empty()){
            if(s.top() != p->val)
                return false;
            s.pop();
            p = p->next;
        }
        return true;
    }
};