Java:

public static Node insert(Node root,int data) {
    Node n = new Node(data);
    Node head = root;
    if (root == null) {
        root = n;
    }
    while (head != null) {
        if (data < head.data && head.left == null) {
            head.left = n;
            break;
        } else if (data < head.data && head.left != null) {
            head = head.left;
        } else if (data >= head.data && head.right != null) {
            head = head.right;
        } else if (data >= head.data && head.right == null) {
            head.right = n;
            break;
        }
    }
    return root;
}