Java recursive solution 100% - O(N) time / O(1) space / O(N) stack call
Feel free to discuss Big-O analysis :)\njava\nclass Solution {\n    public Node connect(Node root) {\n        if (root == null) return null;\n        if (root.l
Feel free to discuss Big-O analysis :)\n```java\nclass Solution {\n    public Node connect(Node root) {\n        if (root == null) return null;\n        if (root.left != null) root.left.next = root.right;\n        if (root.right != null) root.right.next = root.next == null ? null : root.next.left;\n        connect(root.left);\n        connect(root.right);\n        return root;\n    }\n}\n```
['Recursion', 'Java']