Python | Compruebe si algún elemento aparece n veces en la lista dada

Dada una lista, la tarea es encontrar si algún elemento aparece ‘n’ veces en una lista dada de enteros. Básicamente, comprobará el primer elemento que se produce n veces. 
Ejemplos: 
 

Input: l =  [1, 2, 3, 4, 0, 4, 3, 2, 1, 2], n = 3
Output :  2

Input: l =  [1, 2, 3, 4, 0, 4, 3, 2, 1, 2, 1, 1], n = 4
Output :  1

A continuación se muestran algunos métodos para realizar la tarea en Python: 
método 1: uso de iteración y clasificación simples 
 

# Python code to find occurrence of any element
# appearing 'n' times
 
# Input Initialisation
input = [1, 2, 3, 0, 4, 3, 4, 0, 0]
 
# Sort Input
input.sort()
 
# Constants Declaration
n = 3
prev = -1
count = 0
flag = 0
 
# Iterating
for item in input:
    if item == prev:
        count = count + 1
    else:
        count = 1
    prev = item
     
    if count == n:
        flag = 1
        print("There are {} occurrences of {} in {}".format(n, item, input))
        break
 
# If no element is not found.
if flag == 0:
    print("No occurrences found")

Producción : 
 

There are 3 occurrences of 0 in [0, 0, 0, 1, 2, 3, 3, 4, 4]

  
Método 2: Usando Count
 

# Python code to find occurrence of any element
# appearing 'n' times
 
# Input list initialisation
input = [1, 2, 3, 4, 0, 4, 3, 4]
 
# Constant declaration
n = 3
 
# print
print("There are {} occurrences of {} in {}".format(input.count(n), n, input))

Producción : 
 

There are 2 occurrences of 3 in [1, 2, 3, 4, 0, 4, 3, 4]

  
Método 3: Usando defaultdict
Primero llenamos el elemento de la lista en un diccionario y luego encontramos si el recuento de cualquier elemento es igual a n.
 

# Python code to find occurrence of any element
# appearing 'n' times
 
# importing
from collections import defaultdict
 
# Dictionary declaration
dic = defaultdict(int)
 
# Input list initialisation
Input = [9, 8, 7, 6, 5, 9, 2]
 
# Dictionary populate
for i in Input:
    dic[i]+= 1
 
# constant declaration
n = 2
flag = 0
 
# Finding from dictionary
for element in Input:
    if element in dic.keys() and dic[element] == n:
        print("Yes, {} has {} occurrence in {}.".format(element, n, Input))
        flag = 1
        break
 
# if element not found.
if flag == 0:
    print("No occurrences found")

Producción : 
 

Yes, 9 has 2 occurrence in [9, 8, 7, 6, 5, 9, 2]