Solution Exercise 51: list of elements duplicated at least 3 times without using any predefined method in Python

Exercise 51

Write a Python algorithm as a function which takes a list L as a parameter and which returns the list of elements duplicated at least 3 times without using neither the count() method nor any predefined method in Python. (you can use exercise 23)

Solution

# function which determines the number of occurrences of a character in a list
def numberOccurrence (L, a):
    # initialize the number of occurrences of a in L
    numberOcc = 0
    for x in L:
        if x == a:
            numberOcc = numberOcc + 1
    return numberOcc

# function which determines the list of elements duplicated at least 3 times
def duplicate3 (L):
    #initialization of the list of duplicate elements
    ldup = []
    for x in L:
        if (numberOccurrence (L, x) >= 3 and x not in ldup):
            ldup.append (x)
    return ldup

#Example
L = [5, 7, 23, 5, 23, 7, 5, 19, 23, 4, 7, 29, 7]
print (duplicate3 (L)) # the output: [5, 7, 23]