Coding Interview Questions for College Recruitment | 50 Common Problems

Coding interview questions for college recruitment

Cracking a coding interview as a college student can feel like navigating a maze. You’ve studied data structures, solved hundreds of problems online, and maybe even built a few cool projects. But when the interview starts, it all comes down to how well you apply what you know, under pressure.

That’s why the best way to prepare is to get familiar with the actual questions companies ask. The more you see the coding interview patterns, the more confident you become at spotting solutions. Whether you’re aiming for a product-based startup or a big tech company, this list gives you the foundation.

Here’s your guided prep path with the most common coding interview questions for college recruitment, grouped by topic and paired with strategic insights to help you prepare smarter.

Arrays and strings

You’ll often see array-based coding interview questions for college recruitment in early rounds. These questions test how well you use memory, loops, and pointers.

1. Two Sum

Use a hash map to store each number’s complement and index as you iterate. When a match is found, return it.

2. Best Time to Buy and Sell Stock

Track the lowest price seen so far. At each step, calculate the max profit by comparing the current price with the lowest.

3. Maximum Subarray

Apply Kadane’s algorithm. Start with the first element, add the current number to the sum, or reset if it’s lower than the current.

4. Move Zeroes

Use a two-pointer technique: place all non-zero elements at the front, then fill the rest with zeros.

5. Merge Intervals

Sort the intervals. Then iterate and merge overlapping ones by updating the end value when necessary.

6. Longest Substring Without Repeating Characters

Use a sliding window. Track seen characters in a set or map, and adjust the window when duplicates are encountered.

7. Rotate Array

Reverse the entire array. Then reverse the first k and remaining elements separately for a clean in-place rotation.

8. Container With Most Water

Start with two pointers on either end. Move the shorter line inward while keeping track of the max water volume.

Linked lists

These coding interview questions for college recruitment test how well you handle dynamic memory, pointer manipulation, and traversal logic.

9. Reverse a Linked List

Use iterative reversal. Maintain previous and next pointers to reverse links one node at a time.

10. Detect Cycle in a Linked List

Use Floyd’s Cycle Detection Algorithm (slow and fast pointers). If they meet, there’s a loop.

11. Merge Two Sorted Lists

Compare the heads of both lists and build a new list by choosing the smaller node each time.

12. Remove Nth Node From End

Use two pointers. Advance one by N nodes, then move both until the first reaches the end.

Trees and recursion

These coding interview questions for college recruitment explore your understanding of recursive logic and hierarchical structures.

13. Maximum Depth of a Binary Tree

Use recursion. Return the max depth from both left and right subtrees, plus one.

14. Invert Binary Tree

Recursively swap left and right children for every node.

15. Validate Binary Search Tree

Use recursion with min and max value boundaries to ensure each node is correctly placed.

16. Binary Tree Level Order Traversal

Use a queue for breadth-first traversal. Track levels as you dequeue and enqueue children.

Binary search and divide-and-conquer

These are common coding interview questions for college recruitment because they test algorithmic precision.

17. Binary Search

Start with the left and right pointers. Compare the mid-point value, narrow the window until you find the target.

18. Search in Rotated Sorted Array

Apply binary search with logic to detect which half is sorted and adjust the search range accordingly.

19. Find First and Last Position of Element

Use two binary searches: one for the leftmost and another for the rightmost index.

Dynamic programming (DP)

Dynamic programming-based coding interview question for college recruitment tests how well you optimize brute-force logic using memoization or tabulation.

20. Climbing Stairs

Use bottom-up DP to calculate the number of ways to climb the steps. Base cases are 1 and 2.

21. House Robber

Use DP to store the maximum amount at each house. At each house, choose to rob it or skip.

22. Coin Change

Use a DP array where each index represents the minimum coins needed to make that amount.

23. Longest Palindromic Substring

Expand around centers or use a DP table to track whether the substring from i to j is a palindrome.

24. Edit Distance

Use a 2D DP table to track insertion, deletion, and replacement steps between two strings.

Graphs and traversal

Expect at least one graph-based coding interview question for college recruitment in higher-level rounds.

25. Number of Islands

Use DFS or BFS to count islands by marking visited land cells.

26. Clone Graph

Use a hash map to clone each node during DFS or BFS traversal.

27. Course Schedule

Use topological sort to check for cycles in a graph represented by course dependencies.

Stacks and queues

These problems test your ability to simulate data flow and control flow using linear structures.

28. Valid Parentheses

Use a stack to match opening and closing symbols.

29. Min Stack

Use an auxiliary stack to track the current minimum with each push.

30. Implement a Queue Using Stacks

Simulate queue operations using two stacks, reversing order for dequeue.

Bit manipulation

Bit-based logic shows up in some niche coding interview questions for college recruitment.

31. Single Number

Use XOR to cancel out pairs and isolate the single number.

32. Number of 1 Bits

Use bit masking or n = n & (n – 1) to count set bits efficiently.

Math and logic puzzles

You may get a math-heavy coding interview question for college recruitment that demands strong reasoning.

33. FizzBuzz

Loop through 1 to n, print “Fizz” for multiples of 3, “Buzz” for 5, and “FizzBuzz” for both.

34. Palindrome Number

Reverse digits and compare with the original. Watch for overflows or negatives.

35. Pow(x, n)

Use fast exponentiation. Divide the power in half at each step for efficient recursion.

Recursion and backtracking

Many coding interview questions for college recruitment come from this category, especially for companies like Google or Facebook.

36. Subsets

Use backtracking to generate all combinations by including or skipping each element.

37. Permutations

Build permutations by swapping or tracking visited elements in recursion.

38. Combination Sum

Use DFS to explore all paths that sum up to the target using the candidate numbers.

Greedy algorithms

These questions check if you can make local decisions that lead to a global optimum.

39. Jump Game

Track the maximum reachable index as you iterate. If you exceed the last index, return true.

40. Merge Intervals

Sort and merge overlapping intervals using a greedy expansion strategy.

Strings and pattern matching

String manipulation problems are foundational in any coding interview question for college recruitment.

41. Group Anagrams

Use a hash map with a sorted string as the key to group anagrams together.

42. Longest Common Prefix

Compare characters at the same position in all strings until a mismatch is found.

Heap and priority queue

These problems often appear when optimizing access to min/max values.

43. Top K Frequent Elements

Use a hash map for frequency and a min-heap to extract the top k items.

44. Merge K Sorted Lists

Use a heap to efficiently track and merge the smallest elements across lists.

Sliding window

These questions test efficiency with fixed or dynamic window sizes.

45. Maximum Sliding Window

Use a deque to keep track of the maximum elements within a sliding window.

46. Minimum Window Substring

Expand and shrink the window while tracking the frequency of required characters.

Hashing

Mastering hashing helps with problems involving uniqueness or frequency.

47. First Unique Character in a String

Use a hash map to count frequencies, then return the first index with count 1.

48. Intersection of Two Arrays

Use sets to track elements from each array and return the intersection.

Miscellaneous

49. LRU Cache

Implement a doubly linked list with a hash map to achieve O(1) operations.

50. Serialize and Deserialize a Binary Tree

Use pre-order traversal with null markers to encode and decode the tree structure.

Final thoughts

Once you’re done with these 50, check out the full Blind 75 list to level up your prep even further.

Your goal is not to memorize answers. Your goal is to build intuition.

Every question on this list gives you a pattern to learn, a skill to refine, or an edge in a real coding interview. Prepare steadily. Understand deeply. Practice consistently.

If you’re wondering where to begin, pick any topic from the list, open your coding platform, and start with the first question. Track your progress and keep building from there.

Let each question make you better.

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