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Permutation Sequence Test | Pre-employment assessment - Testlify
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Permutation Sequence Test

Overview of Permutation Sequence Test

The problem involves finding the kth permutation of a sequence of numbers from 1 to n. this is done by calculating factorials, determining the position of each digit, and building the permutation iteratively.

Skills measured

  • maths
  • recursion

Available in



Coding Test


35 Mins





Use of Permutation Sequence test

The problem involves finding the kth permutation of a sequence of numbers from 1 to n. This is done by calculating factorials, determining the position of each digit, and building the permutation iteratively.
The approach of the problem is to follows a mathematical approach using factorials and recursive calls to determine the permutation. Here's an overview:

setPerm is a recursive function that constructs the kth permutation.
In the base case, when there's only one element left (n=1), it appends it to the result ans.
It calculates the index where the next element should be taken from using integer division with factVal[n-1].
It handles a corner case where if k is a multiple of the elements in the partition, it decrements the index.
The chosen element is added to the result string, removed from the array v, and k is adjusted accordingly.
The function recursively calls itself with n reduced by one.
In the getPermutation function, it initializes a vector factVal to store factorials.
It initializes an empty string ans and a vector v containing elements from 1 to n.
It calls setPerm to construct the kth permutation and returns the result.

Relevant for

  • Software Developer Engineer
  • Software Developer
  • Software Engineers

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In Permutation Sequence, students learn about permutations and the importance of understanding the order and arrangement of objects or elements. This skill is crucial in various mathematical problems and real-life situations where the order of things matters, such as in probability, combinatorics, and cryptography. By mastering the concept of permutations, students can develop problem-solving skills, logical reasoning, and critical thinking abilities. Understanding permutations also helps students analyze different possibilities, make informed decisions, and organize data efficiently, making it a valuable skill in both mathematical and practical contexts.



Recursion is a fundamental skill covered in the Permutation Sequence problem, as it allows for the systematic generation of all possible permutations of a given set of numbers. By breaking down the problem into smaller subproblems, recursion enables the efficient exploration of all possible combinations without the need for manual enumeration. This skill is crucial for solving complex combinatorial problems, as it simplifies the process of generating permutations and allows for a more elegant and concise solution. Mastering recursion is essential for tackling a wide range of algorithmic challenges in computer science and mathematics.

The Permutation Sequence test is created by a subject-matter expert

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