while (i --> 0)

Question

public int maxDepth(TreeNode root) {
     if (root == null)
         return 0;
     Deque<TreeNode> stack = new LinkedList<>();
     stack.push(root);
     int count = 0;
     while (!stack.isEmpty()) {
         int size = stack.size();
         while (size-- > 0) {
            TreeNode cur = stack.pop();
            if (cur.left != null)
                stack.addLast(cur.left);
            if (cur.right != null)
                stack.addLast(cur.right);
        }
        count++;
    }
    return count;
}

while (i --> 0) 这是什么用法？，第一次遇见

Answer 1

while (i --> 0) 

意思是当前i是否大于0，然后i自减
等价于：

  while (size> 0) {
             size--;
            TreeNode cur = stack.pop();
            if (cur.left != null)
                stack.addLast(cur.left);
            if (cur.right != null)
                stack.addLast(cur.right);
        }