19_Most Consective Repetitions.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(li):
    if not li:
        return None

    Element = ''
    repetitions = 0

    cur = ''
    cur_count = 0

    for element in li:
        if element == cur:
            cur_count += 1
        else:
            if cur_count > repetitions:
                Element = cur
                repetitions = cur_count

            cur = element
            cur_count = 1

    return Element


# 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