Skip to content
Related Articles

Related Articles

Python | Find k longest words in given list
  • Last Updated : 25 Apr, 2019

Given a list of words and a positive integer K, write a Python program to find k longest words in the list in descending order of length.

Examples:

Input : lst  = ['am', 'watermelon', 'girl', 'boy', 'colour'], K = 3
Output : ['watermelon', 'colour', 'girl']

Input : ['see', 'I', 'geek', 'on', 'brain'], K = 4
Output : ['brain', 'geek', 'see', 'on']

 
Method #1 : Using count() from itertools

First, sort the ‘lst’ based on length of the words and then based on a counter variable, so that words occurring later gets higher priority and thus, extract k variables.




# Python3 program to Find 
# longest K words in a list
from itertools import count
  
def longest_word(lst, K):
    cnt = count()
    return sorted(lst, key = lambda w : (len(w), next(cnt)), 
                                        reverse = True)[:K]
  
# Driver code
lst = ['am', 'watermelon', 'girl', 'boy', 'colour']
K = 3
print(longest_word(lst, K))
Output:



['watermelon', 'colour', 'girl']

 
Method #2 : Using sorted()




# Python3 program to Find 
# longest K words in a list
  
def longest_word(lst, K):
    idx, words = zip(*sorted(enumerate(lst), 
    key = lambda w: (-len(w[1]), -w[0]))[:K])
    return list(words)
  
# Driver code
lst = ['am', 'watermelon', 'girl', 'boy', 'colour']
K = 3
print(longest_word(lst, K))
Output:
['watermelon', 'colour', 'girl']

 
Method #3 : Using heap




# Python3 program to Find 
# longest K words in a list
import heapq
from operator import itemgetter
  
def longest_word(lst, K):
    # constructing heap
    heap = [(0, i, '') for i in range(K)]
    heapq.heapify(heap)
  
    # To maintain top K elements
    for i, word in enumerate(lst):
        item = (len(word), i, word)
        if item > heap[0]:
            heapq.heapreplace(heap, item)
  
    return sorted(list(map(itemgetter(2), heap)),
                            key = len, reverse = True)
  
  
# Driver code
lst = ['am', 'watermelon', 'girl', 'boy', 'colour']
K = 3
print(longest_word(lst, K))
Output:
['watermelon', 'colour', 'girl']

 Attention geek! Strengthen your foundations with the Python Programming Foundation Course and learn the basics.  

To begin with, your interview preparations Enhance your Data Structures concepts with the Python DS Course. And to begin with your Machine Learning Journey, join the Machine Learning – Basic Level Course

My Personal Notes arrow_drop_up
Recommended Articles
Page :