def generateUIDs(cids):
    """Generate a list of uid from a list of course ids. uid is hephen-connected ordered course id pairs.
    
    :param cids: course ids
    :type cids: list
    :return: list of unique ids
    :rtype: list
    """
    uids = []
    for i in range(len(cids)):
        for j in range(i, len(cids)):
            ij = cids[i] < cids[j]
            # to ensure the uniqueness of uid
            if ij:
                uids.append(cids[i]+"-"+cids[j])
            else:
                uids.append(cids[j]+"-"+cids[i])
    return uids