Leetcode-234-palindrome linked list

subject

Ideas

1. Linked list is not palindrome , It means that the number may be palindromed . The most direct method is to traverse the array and then judge whether the array returns a palindrome , But such words are too violent and should not be the solution they want .
2. The beginning of palindromes has a feature ： The next one is equal to yourself .
3. incorrect , It may not be equal , But according to the middle node symmetry …
4. It suddenly occurred to me whether I could use the stack , Push the traversal number onto the stack , The stack will pop up while traversing from the beginning , Just judge whether the numbers are equal . But it always feels like the most violent solution .

Code

    public boolean isPalindrome(ListNode head) {
    
        Stack<Integer> s = new Stack<>();
        ListNode temp = head;
        while(temp!=null){
    
            s.push(temp.val);
            temp=temp.next;
        }
        // Start comparing   Re traversal 
        while(head.next!=null){
    
            if(head.val!=s.pop()) return false;
            head=head.next;
        }
        return true;
    }