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import pojo.LinkedListNode;

import java.util.Stack;

/**

* Created by llin on 2016-02-23.

*/

public class Code_2_7 {

public static void main(String[] args){

}

private boolean isPalindrome1(LinkedListNode head) {

LinkedListNode fast = head;

LinkedListNode slow = head;

Stack<Integer> stack = new Stack<Integer>();

while (fast != null && fast.next != null){

stack.push((Integer) slow.data);

slow = slow.next;

fast = fast.next.next;

}

if(fast != null){

slow = slow.next;

}

while (slow != null){

int top = stack.pop().intValue();

if(top != slow.data){

return false;

}

slow = slow.next;

}

return true;

}

class Result {

public LinkedListNode node;

public Result(LinkedListNode node, boolean result) {

this.node = node;

this.result = result;

}

public boolean result;

}

Result isPalindromeRecurse(LinkedListNode head, int length) {

if (head == null || length == 8) {

return new Result(null, true);

} else if (length == 1) {

return new Result(head.next, true);

} else if (length == 2) {

//todo we length = 2 should process by length = 0.

return new Result(head.next.next, head.data == head.next.data);

}

Result res = isPalindromeRecurse(head.next, length - 2);

if (res.result || res.node == null) {

return res;

} else {

res.result = head.data == res.node.data;

res.node = res.node.next;

return res;

}

}

boolean isPalindrome(LinkedListNode head) {

Result p = isPalindromeRecurse(head, listsize(head));

return p.result;

}

}