0234-palindrome-linked-list.java

//reverse the later half
//after reversing just start comparing if at any time the value doesn't match it's not a palindrome, i.e. return false, else it's a palindrome and return true.
//It'll automatically take care of the edge cases of odd and even

classSolution {

publicbooleanisPalindrome(ListNodehead) {
ListNodefast = head;
ListNodeslow = head;
while (fast != null && fast.next != null) {
fast = fast.next.next;
slow = slow.next;
 }
ListNodetemp = reverse(slow);
while (temp != null && head != null) {
if (temp.val != head.val) returnfalse;
temp = temp.next;
head = head.next;
 }
returntrue;
 }

publicListNodereverse(ListNodehead) {
ListNodep = null;
ListNodeq = null;
ListNoder = head;
while (r != null) {
p = q;
q = r;
r = r.next;
q.next = p;
 }
returnq;
 }
}