Max length in array python

I want to check the max length of array elements. Although I can do it with simple code, is there another smart way to implement this in Python 3?

a = [[1,2], [1], [2,2,3,3], [2,2]]
max_len = 0
for d in a:
    max_len = len(d) if len(d) > max_len else max_len
print(max_len)

Mathias711

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asked Mar 16, 2017 at 7:01

2

You can do something like this:

max_len = max([len(i) for i in a])
print(max_len)

answered Mar 16, 2017 at 7:02

Mathias711Mathias711

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You can use the inbuilt max function:

>>> a = [[1,2], [1], [2,2,3,3], [2,2]]
>>> len(max(a, key=len))
4

Mathias711

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answered Mar 16, 2017 at 7:03

HackaholicHackaholic

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Given a list of lists, write a Python program to find the list with maximum length. The output should be in the form (list, list_length). Examples:

Input : [['A'], ['A', 'B'], ['A', 'B', 'C']]
Output : (['A', 'B', 'C'], 3)

Input : [[1, 2, 3, 9, 4], [5], [3, 8], [2]]
Output : ([1, 2, 3, 9, 4], 5)

  Let’s discuss different approaches to solve this problem. 

Approach #1 : Using for loop (Naive) This is a brute force method in which we iterate through each list item(list) and find the list with maximum length. Similarly, we use the for loop to find length of each list and output the maximum length. 

Python3

def FindMaxLength(lst):

    maxList = max((x) for x in lst)

    maxLength = max(len(x) for x in lst )

    return maxList, maxLength

lst = [['A'], ['A', 'B'], ['A', 'B', 'C']]

print(FindMaxLength(lst))

Output:

(['A', 'B', 'C'], 3)

Time Complexity: O(N)
Auxiliary Space: O(1)

  Approach #2: Using map In this method we use Python map function to iterate over the inner lists to create a list of lengths, then get the maximum with max function. 

Python3

def FindMaxLength(lst):

    maxList = max(lst, key = len)

    maxLength = max(map(len, lst))

    return maxList, maxLength

lst = [['A'], ['A', 'B'], ['A', 'B', 'C'], ]

print(FindMaxLength(lst))

Output:

(['A', 'B', 'C'], 3)

Time Complexity: O(N)
Auxiliary Space: O(N)

 Approach #3: Using lambda operator One more method in Python to find the longest length list is the lambda operator. It is used for creating small, one-time and anonymous function objects in Python. Here we pass a variableias argument in the len(i) expression and find the maximum length. 

Python3

def FindMaxLength(lst):

    maxList = max(lst, key = lambda i: len(i))

    maxLength = len(maxList)

    return maxList, maxLength

lst = [['A'], ['A', 'B'], ['A', 'B', 'C']]

print(FindMaxLength(lst))

Output:

(['A', 'B', 'C'], 3)

Time Complexity: O(N)
Auxiliary Space: O(1)

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