[LeetCode]Palindrome Linked List

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?

题解：获得链表一半的位置，再将其反转，最后2个半截的链表比较

public boolean isPalindrome(ListNode head) {

		if(head == null || head.next == null)
			return true;
		ListNode fast=head,slow=head;
		while(fast.next!=null && fast.next.next!=null ){ //slow走到一半的位置
			slow = slow.next;
			fast = fast.next.next;
		}
		     ListNode font = head;  
			slow = reverseList(slow);
		
		while(font!=null){   //两个指针比较
			
			if(font.val != slow.val){
				return false;
			}
			font = font.next;
			slow = slow.next;
		}
		return true;
	}
	public ListNode reverseList(ListNode head){ //将后半截链表反转
		
		ListNode temp = head.next,pre = head;
		while(temp!=null){
			ListNode r = temp.next;
			temp.next = pre;
			pre = temp;
			temp = r;
		}
		head.next = null;
		return pre;
	}

参考： http://blog.youkuaiyun.com/brucehb/article/details/46837209