CodeSignal Technical Assessment Coding Challenges and Practice 4

Question 1

A CodeSignal problem asks for the shortest path in an unweighted graph. Which algorithm should you use?

Accepted Answer

Breadth-first search

Answer

BFS explores nodes level by level, guaranteeing the first time a node is reached is via the shortest path in an unweighted graph.

Question 2

You need to compute the nth Fibonacci number efficiently using dynamic programming. What is the time and space complexity of the tabulation (bottom-up) approach?

Accepted Answer

O(n) time, O(1) space with two variables

Answer

Using only two rolling variables to store the previous two results gives O(n) time and O(1) space.

Question 3

In a CodeSignal assessment, you're asked to check if a string is a palindrome ignoring non-alphanumeric characters. What is the most efficient approach?

Accepted Answer

Two-pointer technique from both ends

Answer

Two pointers starting at each end and skipping non-alphanumeric characters compare in O(n) time and O(1) space.

Question 4

What distinguishes a stable sorting algorithm from an unstable one?

Accepted Answer

Stable sorts preserve the relative order of equal elements

Answer

A stable sort guarantees that records with equal keys appear in their original input order in the sorted output.

Question 5

A CodeSignal problem requires computing the maximum profit from one buy-sell of a stock given daily prices. What algorithmic approach solves this in O(n)?

Accepted Answer

Track the running minimum buy price and maximum profit in one pass

Answer

One pass tracking the minimum price seen so far and updating max profit at each step achieves O(n) time and O(1) space.

Codesignal Practice Test

Codesignal Practice Test

CodeSignal Technical Assessment Coding Challenges and Practice 4