二叉树的最大深度 about pisecespeng.record.me HOT 2 CLOSED

class TreeNode {
    int val;
    TreeNode left;
    TreeNode right;
    TreeNode() { }
    TreeNode(int val) { this.val = val; }
}

public static int func(TreeNode root) {
    if (null == root) return 0;
    return Math.max(func(root.left) + 1, func(root.right) + 1);
}

class TreeNode {
    int val;
    TreeNode left;
    TreeNode right;
    TreeNode() { }
    TreeNode(int val) { this.val = val; }
}

public static int func(TreeNode root) {
    if (root == null) {
        return 0;
    }
    Queue<TreeNode> queue = new LinkedList<TreeNode>();
    queue.offer(root);
    int ans = 0;
    while (!queue.isEmpty()) {
        int size = queue.size();
        while (size > 0) {
            TreeNode node = queue.poll();
            if (node.left != null) {
                queue.offer(node.left);
            }
            if (node.right != null) {
                queue.offer(node.right);
            }
            size--;
        }
        ans++;
    }
    return ans;
}