题解 | #链表的回文结构#

/*
struct ListNode {
    int val;
    struct ListNode *next;
    ListNode(int x) : val(x), next(NULL) {}
};*/
class PalindromeList {
public:
    bool chkPalindrome(ListNode* head) {
        // write code here

        //找到中间结点slow
        struct ListNode* fast = head;
        struct ListNode* slow = head;
        while(fast && fast->next)
        {
            fast = fast->next->next;
            slow = slow->next;
        }
        

        //逆置中间结点以后的指针
        struct ListNode* cur = slow;
        struct ListNode* prev = NULL;
        while(cur)
        {
            struct ListNode* next = cur->next;
            cur->next = prev;
            prev = cur;
            cur = next;
        }
        
        struct ListNode* head2 = prev;//head2指向逆置后的第一个几点

        //挨个对比
        while (head2 && head) 
        {
            if(head2->val != head->val)
            {
                return false;
            }
            head = head->next;
            head2 = head2->next;
        }
        return true;
    }
};