Data Structures & Algorithms Quiz

Given an array sorted in non-decreasing order, what’s the best time to check if a number exists?

• O(n)

• O(log n)

• O(n log n)

• O(1)

To remove duplicates from a sorted array in-place, which two-pointer approach is used?

• Fast slower pointers

• Merge sort

• Hashing

• Backtracking

Time complexity to reverse a string of length n?

• O(1)

• O(log n)

• O(n)

• O(n²)

For checking if one string is an anagram of another (both length n), best approach?

• Bubble sort + compare (O(n²))

• Hash map count (O(n))

• Binary search

• Merge sort + compare

What’s the time to find the longest prefix common to n strings (each of avg length m)?

• O(n + m)

• O(n × m)

• O(log(nm))

• O(n m log m)

Removing the n-th node from the end can be done in:

• O(n²)

• O(n log n)

• O(n) using two pointers

• O(log n)

To detect a cycle in a linked list, which algorithm is used?

• Hashmap

• Sorting

• Floyd’s cycle-finding

• Backtracking

Merge two sorted singly-linked lists into one sorted list — time complexity?

• O(n²)

• O(n + m)

• O(n log n)

• O(n)

Reverse a singly-linked list — iterative in-place method?

• Use stack

• 3-pointer technique

• Node swapping

• Bubble comparisons

To check if a linked list is palindrome – what’s efficient?

• Push all values to stack – O(n)

• Use two-pointer + reverse second half – O(1) space

• Convert to array

• Recursion only