Python: Find the longest string of a list of strings

Last update on May 28 2022 13:41:42 (UTC/GMT +8 hours)

Python Programming Puzzles: Exercise-15 with Solution

Write a Python program find the longest string of a given list of strings.

Input:
['cat', 'car', 'fear', 'center']
Output:
center

Input:
['cat', 'dog', 'shatter', 'donut', 'at', 'todo', '']
Output:
shatter

Pictorial Presentation:

Python: Find the longest string of a list of strings.

Sample Solution-1:

Python Code:

def test(words):
    return  max(words, key=len) 
strs =  ['cat', 'car', 'fear', 'center']
print("Original strings:")
print(strs)
print("Longest string of the said list of strings:")
print(test(strs))
strs =  ['cat', 'dog', 'shatter', 'donut', 'at', 'todo', '']
print("\nOriginal strings:")
print(strs)
print("Longest string of the said list of strings:")
print(test(strs))

Sample Output:

Original strings:
['cat', 'car', 'fear', 'center']
Longest string of the said list of strings:
center

Original strings:
['cat', 'dog', 'shatter', 'donut', 'at', 'todo', '']
Longest string of the said list of strings:
shatter

Flowchart:

Visualize Python code execution:

The following tool visualize what the computer is doing step-by-step as it executes the said program:

Sample Solution-2:

Python Code:

#License: https://bit.ly/3oLErEI

def test(words):
    alphabet = "abcdefghijklmnopqrstuvwxyz"
    alphabet = alphabet + alphabet.upper()
    alphabet_dict = {}
    for k in alphabet:
        alphabet_dict[k] = True
    alphabet_set = set(alphabet)
    max_word = words[0]
    for el in words:
        if not ((set(el) <= alphabet_set) and (set(el) == set(el).intersection(alphabet_dict.keys()))):
            continue
        if len(el) >= len(max_word):
            max_word = el
    return max_word
strs =  ['cat', 'car', 'fear', 'center']
print("Original strings:")
print(strs)
print("Longest string of the said list of strings:")
print(test(strs))
strs =  ['cat', 'dog', 'shatter', 'donut', 'at', 'todo', '']
print("\nOriginal strings:")
print(strs)
print("Longest string of the said list of strings:")
print(test(strs))

Sample Output:

Original strings:
['cat', 'car', 'fear', 'center']
Longest string of the said list of strings:
center

Original strings:
['cat', 'dog', 'shatter', 'donut', 'at', 'todo', '']
Longest string of the said list of strings:
shatter

Flowchart:

Visualize Python code execution:

The following tool visualize what the computer is doing step-by-step as it executes the said program:

Python Code Editor :

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Previous: Find the lengths of a list of non-empty strings.
Next: Find the strings in a list containing a given substring.

Python: Tips of the Day

Find current directory and file's directory:

To get the full path to the directory a Python file is contained in, write this in that file:

import os dir_path = os.path.dirname(os.path.realpath(__file__))

(Note that the incantation above won't work if you've already used os.chdir() to change your current working directory, since the value of the __file__ constant is relative to the current working directory and is not changed by an os.chdir() call.)

To get the current working directory use

import os cwd = os.getcwd()

Documentation references for the modules, constants and functions used above:

The os and os.path modules.

The __file__ constant

os.path.realpath(path) (returns "the canonical path of the specified filename, eliminating any symbolic links encountered in the path")

os.path.dirname(path) (returns "the directory name of pathname path")

os.getcwd() (returns "a string representing the current working directory")

os.chdir(path) ("change the current working directory to path")

Ref: https://bit.ly/3fy0R6m