234. 迴文連結串列

LeetCode： 234. 迴文連結串列

類似雙指標

前後對比

    public boolean isPalindrome(ListNode head) {
        if(head == null || head.next == null) return true;
        ListNode left = head, right = head;
        Stack<ListNode> s = new Stack<>();

        while(right.next != null){
            s.push(right);
            right = right.next;
        }
        // right 指向了最後一個元素

        int cnt = s.size() + 1;
        for (int i = 0; i < cnt / 2; i++) {
            if(left.val != right.val) return false;
            left = left.next;
            right = s.pop();
        }

        return true;
    }