# Python – Skew Nested Tuple Summation

• Last Updated : 02 Sep, 2020

Given a Tuple, nesting at 2nd position, return summation of 1st elements.

Input : test_tup = (5, (6, (1, (9, None))))
Output : 21
Explanation : 9 + 6 + 5 + 1 = 21.

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Input : test_tup = (5, (6, (1, None)))
Output : 12
Explanation : 1 + 6 + 5 = 12.

Method #1 : Using infinite loop

In this, we perform get into skew structure while summation using infinite loop and break when we reach None value.

## Python3

 `# Python3 code to demonstrate working of ``# Skew Nested Tuple Summation``# Using infinite loop`` ` `# initializing tuple``test_tup ``=` `(``5``, (``6``, (``1``, (``9``, (``10``, ``None``)))))`` ` `# printing original tuple``print``(``"The original tuple is : "` `+` `str``(test_tup))`` ` `res ``=` `0``while` `test_tup:``    ``res ``+``=` `test_tup[``0``]``     ` `    ``# assigning inner tuple as original``    ``test_tup ``=` `test_tup[``1``]`` ` `# printing result ``print``(``"Summation of 1st positions : "` `+` `str``(res)) `
Output
```The original tuple is : (5, (6, (1, (9, (10, None)))))
Summation of 1st positions : 31

```

Method #2 : Using recursion

In this, we perform summation and recur for the 2nd element of tuple,  return on None.

## Python3

 `# Python3 code to demonstrate working of ``# Skew Nested Tuple Summation``# Using recursion`` ` `# helper function to perform task``def` `tup_sum(test_tup):``     ` `    ``# return on None ``    ``if` `not` `test_tup:``        ``return` `0``    ``else``:``        ``return` `test_tup[``0``] ``+` `tup_sum(test_tup[``1``])`` ` `# initializing tuple``test_tup ``=` `(``5``, (``6``, (``1``, (``9``, (``10``, ``None``)))))`` ` `# printing original tuple``print``(``"The original tuple is : "` `+` `str``(test_tup))`` ` `# calling fnc.``res ``=` `tup_sum(test_tup)`` ` `# printing result ``print``(``"Summation of 1st positions : "` `+` `str``(res)) `
Output
```The original tuple is : (5, (6, (1, (9, (10, None)))))
Summation of 1st positions : 31

```

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