給定一個單鏈表,確定它是否是回文的。
跟進:
你可以在O(n)時間和O(1)空間下完成它嗎?
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?
bool judge(ListNode *head, ListNode* &cur) {
if (!head)
return true;
if (!judge(head->next, cur))
return false;
if (cur->val != head->val)
return false;
else {
cur = cur->next;
return true;
}
}
bool isPalindrome(ListNode* head) {
ListNode *cur = head;
return judge(head, cur);
}