checkio2.py

def checkio(data):
    #Your code here
    #It's main function. Don't remove this function
    #It's using for auto-testing and must return a result for check.  

    #replace this for solution
    sorted_pairs = sorted(enumerate(data),None,lambda (index, element): element)
    count = len(data)
    if count == 1:
        return []
    
    nonuniq_sorted_pairs = map(lambda (prev, this, next): this, filter(lambda (prev, this, next): prev[1]==this[1] or next[1]==this[1], zip(sorted_pairs,sorted_pairs[1:],sorted_pairs[2:])))
    if sorted_pairs[0][1]==sorted_pairs[1][1]:
        nonuniq_sorted_pairs.append(sorted_pairs[0])
    if sorted_pairs[count-2][1]==sorted_pairs[count-1][1]:
        nonuniq_sorted_pairs.append(sorted_pairs[count-1])
    return map(lambda (index, element): element, sorted(nonuniq_sorted_pairs,None,lambda (index, element): index))