CrowdStrike Interview Guide

#1. String Compression

ArraysTwo PointersStrings

Compress a given string by replacing consecutive repeating characters with the character followed by the count of repetitions. If the compressed string isn't shorter, return the original.

This question is very likely to be asked in your CrowdStrike interview

Encode and Decode Strings

Design an algorithm to encode a list of strings into a single string and then decode the single string back to the original list of strings.

ArraysStrings

Very likely

If you have a CrowdStrike interview, it's very likely that you will get this question

#2. Encode and Decode Strings

This question is very likely to be asked in your CrowdStrike interview

Design an algorithm to encode a list of strings into a single string and then decode the single string back to the original list of strings.

ArraysStrings

Time Based Key-Value Store

Design a key-value store that supports storing values associated with timestamps. You should be able to retrieve the value for a given key at the latest timestamp less than or equal to a given time.

ArraysBinary Search

Somewhat likely

If you have a CrowdStrike interview, you might get this question

#3. Time Based Key-Value Store

This question is somewhat likely to be asked in your CrowdStrike interview

Design a key-value store that supports storing values associated with timestamps. You should be able to retrieve the value for a given key at the latest timestamp less than or equal to a given time.

ArraysBinary Search

Trapping Rain Water

Given an array representing the height of bars, calculate how much water can be trapped between them after rain. Think about finding the maximum height to the left and right of each bar.

ArraysTwo PointersDynamic ProgrammingStacks

Somewhat likely

If you have a CrowdStrike interview, you might get this question

Hard

#4. Trapping Rain Water

Hard

Given an array representing the height of bars, calculate how much water can be trapped between them after rain. Think about finding the maximum height to the left and right of each bar.

ArraysTwo PointersDynamic ProgrammingStacks

This question is somewhat likely to be asked in your CrowdStrike interview

Merge Intervals

You are given a collection of intervals. Merge all overlapping intervals into a single interval and return the result.

ArraysTwo PointersSorting

Somewhat likely

If you have a CrowdStrike interview, you might get this question

#5. Merge Intervals

ArraysTwo PointersSorting

You are given a collection of intervals. Merge all overlapping intervals into a single interval and return the result.

This question is somewhat likely to be asked in your CrowdStrike interview

Move Zeroes

Given an array, rearrange it so that all zeros are moved to the end while maintaining the relative order of the non-zero elements.

If you have a CrowdStrike interview, it's unlikely that you will get this question. CrowdStrike does ask it, but it's rare

#6. Move Zeroes

Given an array, rearrange it so that all zeros are moved to the end while maintaining the relative order of the non-zero elements.

This question is not likely to be asked in your CrowdStrike interview

Valid Parentheses

Determine if a string containing parentheses is valid. A valid string has matching and properly nested opening and closing parentheses.

StringsStacks

If you have a CrowdStrike interview, it's unlikely that you will get this question. CrowdStrike does ask it, but it's rare

#7. Valid Parentheses

This question is not likely to be asked in your CrowdStrike interview

Determine if a string containing parentheses is valid. A valid string has matching and properly nested opening and closing parentheses.

StringsStacks

Number of Islands

Given a grid representing land and water, count the number of distinct islands. An island is formed by connected land cells.

ArraysGraphs

If you have a CrowdStrike interview, it's unlikely that you will get this question. CrowdStrike does ask it, but it's rare

#8. Number of Islands

This question is not likely to be asked in your CrowdStrike interview

Given a grid representing land and water, count the number of distinct islands. An island is formed by connected land cells.

ArraysGraphs

Course Schedule

Determine if it is possible to finish all courses given prerequisites. Some courses must be taken before others; can you find a valid order?

Graphs

If you have a CrowdStrike interview, it's unlikely that you will get this question. CrowdStrike does ask it, but it's rare

#9. Course Schedule

This question is not likely to be asked in your CrowdStrike interview

Determine if it is possible to finish all courses given prerequisites. Some courses must be taken before others; can you find a valid order?

Graphs

Squares of a Sorted Array

You're given a sorted array of integers. Return a new array containing the squares of each number, also sorted in non-decreasing order.

If you have a CrowdStrike interview, it's unlikely that you will get this question. CrowdStrike does ask it, but it's rare

#10. Squares of a Sorted Array

You're given a sorted array of integers. Return a new array containing the squares of each number, also sorted in non-decreasing order.

This question is not likely to be asked in your CrowdStrike interview

Best Time to Buy and Sell Stock

You're given daily stock prices. Find the maximum profit you can make by buying and selling the stock once. You must buy before you sell.

ArraysTwo PointersDynamic Programming

If you have a CrowdStrike interview, it's unlikely that you will get this question. CrowdStrike does ask it, but it's rare

#11. Best Time to Buy and Sell Stock

ArraysTwo PointersDynamic Programming

You're given daily stock prices. Find the maximum profit you can make by buying and selling the stock once. You must buy before you sell.

This question is not likely to be asked in your CrowdStrike interview

Spiral Matrix

Traverse a given matrix in a spiral pattern, returning all elements in the order you visit them. Essentially, walk around the matrix layer by layer, adding elements to a list.

If you have a CrowdStrike interview, it's unlikely that you will get this question. CrowdStrike does ask it, but it's rare

#12. Spiral Matrix

Traverse a given matrix in a spiral pattern, returning all elements in the order you visit them. Essentially, walk around the matrix layer by layer, adding elements to a list.