The Java implementation finds the depth and width of the binary tree

This is a common binary tree operation. To summarize:

Set the data structure of the node as follows:

class TreeNode {

    char val;

    TreeNode left = null;

    TreeNode right = null;
    TreeNode(char _val) {

        this.val = _val;

    }

}

1. Binary tree depth

In this case, we can use recursion to find the depth of the left subtree and the depth of the right subtree respectively. The larger value of the two depths is +1.

//Gets the maximum depth 

    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);

        }

    }

2. Binary tree width

Using queues, the binary tree is traversed hierarchically. After traversing the previous layer, all the nodes of the next layer have been put into the queue, and the number of elements in the queue is the width of the next layer. The maximum width of the binary tree can be obtained by traversing the next layer in turn.

//Gets the maximum width 

    public static int getMaxWidth(TreeNode root) {

        if (root == null)

            return 0;
        Queue<TreeNode> queue = new ArrayDeque<TreeNode>();

        int maxWitdth = 1; //Maximum width 

        queue.add(root); //The team
        while (true) {

            int len = queue.size(); //The number of nodes in the current layer is 

            if (len == 0)

                break;

            while (len > 0) {//If the current layer, there are also nodes 

                TreeNode t = queue.poll();

                len--;

                if (t.left != null)

                    queue.add(t.left); //Next layer node enqueue 

                if (t.right != null)

                    queue.add(t.right);//Next layer node enqueue 

            }

            maxWitdth = Math.max(maxWitdth, queue.size());

        }

        return maxWitdth;

    }