trip_advisor_tree.py

class Node(object):
    def __init__(self, name, lc=None, rc=None):
        self.name = name
        self.lc = lc
        self.rc = rc
        self.rn = None

    # THE MEAT OF THE PROBLEM
    @staticmethod
    def link_rn(level_list):
        lower_level_list = []
        level_list_length = len(level_list)

        if level_list_length == 0:
            return

        for i in range(level_list_length):
            cur_node = level_list[i]
            if i + 1 < level_list_length: # if there's a right neighbor
                right_node = level_list[i + 1]
                cur_node.rn = right_node
            if cur_node.lc:
                lower_level_list.append(cur_node.lc)
            if cur_node.rc:
                lower_level_list.append(cur_node.rc)

        Node.link_rn(lower_level_list)

def print_right_neighbors(nodes):
    for node in nodes:
        if node.rn:
            rn_name = node.rn.name
        else:
            rn_name = 'None'

        print('%s -> %s' % (node.name, rn_name))

if __name__ == '__main__':
    D, E, F, G = Node('D'), Node('E'), Node('F'), Node('G')
    B, C       = Node('B', D, E), Node('C', F, G)
    A          = Node('A', B, C)

    all_nodes = [A, B, C, D, E, F, G]

    print 'With no right linkage'
    print '====================='
    print_right_neighbors(all_nodes)

    starter_level_list  =[A]
    Node.link_rn(starter_level_list)

    print
    print 'With right linkage'
    print '====================='
    print_right_neighbors(all_nodes)


    # OUTPUT
    # With no right linkage
    # =====================
    # A -> None
    # B -> None
    # C -> None
    # D -> None
    # E -> None
    # F -> None
    # G -> None

    # With right linkage
    # =====================
    # A -> None
    # B -> C
    # C -> None
    # D -> E
    # E -> F
    # F -> G
    # G -> None