CodeSignal Technical Assessment Array and String Manipulation 2

Question 1

Given an array [3, 1, 4, 1, 5, 9, 2, 6], what is the result of rotating it left by 3 positions?

Accepted Answer

[1, 5, 9, 2, 6, 3, 1, 4]

Answer

[9, 2, 6, 3, 1, 4, 1, 5]

Answer

[4, 1, 5, 9, 2, 6, 3, 1]

Answer

[6, 3, 1, 4, 1, 5, 9, 2]

Question 2

Which algorithm finds the maximum subarray sum in O(n) time?

Accepted Answer

Kadane's Algorithm

Answer

Boyer-Moore Algorithm

Answer

KMP Algorithm

Answer

Floyd-Warshall Algorithm

Question 3

What does the following produce for s = 'abcde': s[1:4]?

Accepted Answer

'bcd'

Answer

'bcde'

Answer

'abc'

Answer

'abcd'

Question 4

What is the time complexity of checking whether two strings are anagrams by sorting both?

Accepted Answer

O(n log n)

Answer

O(n)

Answer

O(n²)

Answer

O(1)

Question 5

An array contains integers 1–n with one duplicate and one missing value. Which approach finds both in O(n) time and O(1) space?

Accepted Answer

Use XOR and arithmetic sum/sum-of-squares formulas

Answer

Sort and scan for adjacent duplicates

Answer

Use a hash set to track seen values

Answer

Nested loops comparing every pair

Question 6

Given strings s = 'racecar', which single operation verifies it is a palindrome most efficiently?

Accepted Answer

Compare s with s[::-1]

Answer

Reverse s character by character and compare

Answer

Sort s and compare with the original

Answer

Count character frequencies

Question 7

When merging two sorted arrays of sizes m and n into a single sorted array, what is the optimal time complexity?

Accepted Answer

O(m + n)

Answer

O(m · n)

Answer

O((m + n) log(m + n))

Answer

O(max(m, n))