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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']
```

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