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# Question 8: Longest Repetition

# Define a procedure, longest_repetition, that takes as input a
# list, and returns the element in the list that has the most
# consecutive repetitions. If there are multiple elements that
# have the same number of longest repetitions, the result should
# be the one that appears first. If the input list is empty,
# it should return None.

def longest_repetition(ls):
    if ls == []:
        return None
    appearance = 1
    max_number = 1
    e = ls[0]
    for i in range(1, len(ls)):
        if ls[i] == ls[i-1]:
            appearance += 1
            if appearance > max_number:
                max_number = appearance
                e = ls[i]
        else:
            appearance = 1
    return e

print longest_repetition([2, 2, 3, 3, 3])
# Incorrect. Your procedure did not return
#     `3` for the input
#     `[2, 2, 3, 3, 3]`.

#For example,

# print longest_repetition([1, 2, 2, 3, 3, 3, 2, 2, 1])
# # 3
#
# print longest_repetition(['a', 'b', 'b', 'b', 'c', 'd', 'd', 'd'])
# # b
#
# print longest_repetition([1,2,3,4,5])
# # 1
#
# print longest_repetition([])
# None