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

Jun 5, 2021

#### 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 listdef 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 timesdef 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#ExampleL = [5, 7, 23, 5, 23, 7, 5, 19, 23, 4, 7, 29, 7]print (duplicate3 (L)) # the output: [5, 7, 23]``
Younes Derfoufi
my-courses.net