L27Q6_LongestRepitition.py

# 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(input_list):
    bestElement = None
    current = None
    length = 0
    current_length = 0
    for element in input_list:
        if current != element:
            current = element
            current_length = 1
        else:
            current_length += 1
        if current_length > length:
            bestElement = current
            length = current_length
    return bestElement

#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