Given the head of a singly linked list, return true if it is a
or false otherwise.
Example 1:
Input: head = [1,2,2,1] Output: true
Example 2:
Input: head = [1,2] Output: false
Constraints:
[1, 105].0 <= Node.val <= 9
class Solution {
public boolean isPalindrome(ListNode head) {
Stack<Integer> st = new Stack<>();
ListNode ptr = head ;
while(ptr!=null){
st.push(ptr.val);
ptr = ptr.next;
}
ListNode ptr2 = head ;
while(ptr2!=null){
int val1 = ptr2.val;
int val2 = st.pop();
if(val1 != val2 ){
return false ;
}
ptr2 = ptr2.next;
}
return true ;
}
}
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