class TreeNode {     char val;     TreeNode left = null;     TreeNode right = null;     TreeNode(char _val) {         this.val = _val;     } }

// 获取最大深度     public static int getMaxDepth(TreeNode root) {         if (root == null)             return 0;         else {             int left = getMaxDepth(root.left);             int right = getMaxDepth(root.right);             return 1 + Math.max(left, right);         }     }

// 获取最大宽度     public static int getMaxWidth(TreeNode root) {         if (root == null)             return 0;         Queue<TreeNode> queue = new ArrayDeque<TreeNode>();         int maxWitdth = 1; // 最大宽度         queue.add(root); // 入队         while (true) {             int len = queue.size(); // 当前层的节点个数             if (len == 0)                 break;             while (len > 0) {// 如果当前层，还有节点                 TreeNode t = queue.poll();                 len--;                 if (t.left != null)                     queue.add(t.left); // 下一层节点入队                 if (t.right != null)                     queue.add(t.right);// 下一层节点入队             }             maxWitdth = Math.max(maxWitdth, queue.size());         }         return maxWitdth;     }