题解 | #判断一个链表是否为回文结构#

#include <stdbool.h>
struct ListNode* reverse(struct ListNode* head)
{
    if(!head || !head->next)
    {
        return head;
    }
    struct ListNode *q,*p;
    p = head;
    q = head->next;
    head->next = NULL;
    while(p)
    {
        p = q->next;
        q->next = head;
        head = q;
        q = p;
    }
    return head;

}
bool isPail(struct ListNode* head ) {
    // write code here
    struct ListNode* nhead = (struct ListNode*)malloc(sizeof(struct ListNode));
    
    nhead->val = head->val;
    struct ListNode* tmp = nhead;
    struct ListNode* tmp1 = head->next;
    while(tmp1)
    {
         struct ListNode* node = (struct ListNode*)malloc(sizeof(struct ListNode));
         node->val = tmp1->val;
         tmp->next = node;
         tmp = tmp->next;
         tmp1 = tmp1->next;
    }
    nhead = reverse(nhead);
    while(head)
    {
        if(head->val != nhead->val)
        {
            return false;
        }
        head=head->next;
        nhead=nhead->next;
    }
    return true;
}