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# Python – Alternate elements Similarity

• Last Updated : 01 Aug, 2020

Given list of elements, check if all the alternate elements are equal to K.

Input : test_list = [5, 3, 5, 2, 5, 8, 9], K = 5
Output : False
Explanation : 9 != 5, hence False.

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Input : test_list = [4, 3, 4, 2, 4], K = 4
Output : True
Explanation : All alternates equal to 4.

Method #1 : Using loop

This is brute way to solution to this problem. In this, iterate for each element in list and check for each element if they are equal to K.

## Python3

 `# Python3 code to demonstrate working of ``# Alternate elements Similarity``# Using loop`` ` `# initializing lists``test_list ``=` `[``5``, ``3``, ``5``, ``2``, ``5``, ``8``, ``5``]`` ` `# printing original list``print``(``"The original list : "` `+` `str``(test_list))`` ` `# initializing K ``K ``=` `5`` ` `# using flag to Flag false if any one element is not K ``# using loop to check for each element``res ``=` `True``for` `idx, ele ``in` `enumerate``(test_list):``    ``if` `not` `idx ``%` `2` `and` `ele !``=` `K: ``        ``res ``=` `False` `        ``break`` ` `# printing result ``print``(``"Are all alternate elements equal to K : "` `+` `str``(res))`
Output
```The original list : [5, 3, 5, 2, 5, 8, 5]
Are all alternate elements equal to K : True
```

Method #2 : Using all() + generator expression

This is yet another way in which this task can be performed. In this, we check for all elements using all() and generator expression is used for condition check and iteration.

## Python3

 `# Python3 code to demonstrate working of ``# Alternate elements Similarity``# Using all() + generator expression`` ` `# initializing lists``test_list ``=` `[``5``, ``3``, ``5``, ``2``, ``5``, ``8``, ``5``]`` ` `# printing original list``print``(``"The original list : "` `+` `str``(test_list))`` ` `# initializing K ``K ``=` `5`` ` `# all() to encapsulate whole logic into one expression``res ``=` `all``(test_list[idx] ``=``=` `K ``for` `idx ``in` `range``(``0``, ``len``(test_list), ``2``))`` ` `# printing result ``print``(``"Are all alternate elements equal to K : "` `+` `str``(res))`
Output
```The original list : [5, 3, 5, 2, 5, 8, 5]
Are all alternate elements equal to K : True
```

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