# Python | Remove and print every third from list until it becomes empty

• Difficulty Level : Hard
• Last Updated : 21 Nov, 2018

Given a list of numbers, Your task is to remove and print every third number from a list of numbers until the list becomes empty.
Examples:

Input : [10, 20, 30, 40, 50, 60, 70, 80, 90]
Output : 30 60 90 40 80 50 20 70 10
Explanation:
The first third element encountered is 30, after 30 we start the count from 40 for the next third element which is 60, after that 90 is encountered. Then again the count starts from 10 for the next third element which is 40. Proceeding in the same manner as we did before we get next third element after 40 is 80. This process is repeated until the list becomes empty.

Input : [1, 2, 3, 4]
Output : 3 2 4 1
Explanation:
The first third element encountered is 3, after 3 we start the count from 4 for the next third element which is 2. Then again the count starts from 4 for the next third element which is 4 itself and finally the last element 1 is printed.

## Recommended: Please try your approach on {IDE} first, before moving on to the solution.

Approach The index of the list starts from 0 and the first third element will be at position 2. Traverse till the list becomes empty and each time find the index of the next third element and print its corresponding value. After printing reduce the length of the list.

 `# Python program to remove to every third``# element until list becomes empty``def` `removeThirdNumber(int_list):``     ` `    ``# list starts with``    ``# 0 index``    ``pos ``=` `3` `-` `1``    ``index ``=` `0``    ``len_list ``=` `(``len``(int_list))``     ` `    ``# breaks out once the``    ``# list becomes empty``    ``while` `len_list > ``0``: ``     ` `        ``index ``=` `(pos ``+` `index) ``%` `len_list``         ` `        ``# removes and prints the required``        ``# element``        ``print``(int_list.pop(index)) ``        ``len_list ``-``=` `1`` ` `# Driver code``nums ``=` `[``1``, ``2``, ``3``, ``4``] ``removeThirdNumber(nums)`

Output:

```3
2
4
1
```
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