【回文串7】LeetCode 234. Palindrome Linked List

LeetCode 234. Palindrome Linked List

Solution1：我的答案
一遍过，哈哈哈！

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
class Solution {
public:
    bool isPalindrome(ListNode* head) {
        if (!head || !head->next) return true;//题目无明确要求，暂认为空指针是回文串
        stack<struct ListNode*> temp_stack;
        int num_listnode = 0;
        struct ListNode *cur = head;
        while (cur) {
            num_listnode++;
            cur = cur->next;
        }
        //把前半段链表装到栈里头
        int i = 1; cur = head;
        while (i <= num_listnode/2) {
            temp_stack.push(cur);
            cur = cur->next;
            i++;
        }
        if (num_listnode % 2 == 1) cur = cur->next;
        while (!temp_stack.empty()) {
            if (cur->val != temp_stack.top()->val)
                return false;
            else {
                cur = cur->next;
                temp_stack.pop();
            }
        }
        return true;
    }
};