Unacademy Placement Papers 2025

Overview

This page is a working set of Unacademy placement papers from 2025: from student reports questions, the 2025 online assessment pattern, and step-by-step solutions. Use it to see what Unacademy actually asked in the latest cycle, how hard the rounds were, and which themes (DSA, system design, aptitude, or role-specific topics) mattered most. Practice the problems below under timed conditions, then cross-check with the interview and preparation guides if you are targeting an upcoming Unacademy drive.

Unacademy Online Assessment 2025 pattern

Section	Questions	Time	Difficulty
Coding Problems	2-3	90 min	Medium-Hard

Unacademy Placement Papers 2025 - actual questions & solutions

This section contains practice questions styled on Unacademy placement papers 2025 (recent-cycle pattern), with worked solutions. Use them as timed sectional drills - from student reports drives vary by college and role, so treat this as a high-signal practice bank, not an official paper dump.

Question 1: first non-repeating character

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Problem Statement: Return the first non-repeating character in a string, or ‘_’ if none.

Example:

Input: "swiss"
Output: 'w'

Solution (Java):

public char firstUnique(String s) {
    int[] freq = new int[256];
    for (char c : s.toCharArray()) freq[c]++;
    for (char c : s.toCharArray()) if (freq[c] == 1) return c;
    return '_';
}

Time Complexity: O(n)
Space Complexity: O(1)

Question 2: rotate array right by k

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Problem Statement: Rotate the array to the right by k steps.

Example:

Input: [1,2,3,4,5,6,7], k = 3
Output: [5,6,7,1,2,3,4]

Solution (Java):

public void rotate(int[] nums, int k) {
    k %= nums.length;
    reverse(nums, 0, nums.length - 1);
    reverse(nums, 0, k - 1);
    reverse(nums, k, nums.length - 1);
}
void reverse(int[] a, int l, int r) {
    while (l < r) { int t = a[l]; a[l++] = a[r]; a[r--] = t; }
}

Time Complexity: O(n)
Space Complexity: O(1)

Question 3: two sum

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Problem Statement: Given an array of integers and a target, return indices of two numbers that add up to target.

Example:

Input: nums = [2, 7, 11, 15], target = 9
Output: [0, 1]

Solution (Java):

public int[] twoSum(int[] nums, int target) {
    Map<Integer, Integer> map = new HashMap<>();
    for (int i = 0; i < nums.length; i++) {
        int need = target - nums[i];
        if (map.containsKey(need)) return new int[]{map.get(need), i};
        map.put(nums[i], i);
    }
    return new int[]{};
}

Time Complexity: O(n)
Space Complexity: O(n)

Question 4: binary tree level order

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Problem Statement: Return the level-order traversal of a binary tree.

Example:

Input: [3,9,20,null,null,15,7]
Output: [[3],[9,20],[15,7]]

Solution (Java):

public List<List<Integer>> levelOrder(TreeNode root) {
    List<List<Integer>> res = new ArrayList<>();
    if (root == null) return res;
    Queue<TreeNode> q = new ArrayDeque<>();
    q.add(root);
    while (!q.isEmpty()) {
        int sz = q.size();
        List<Integer> level = new ArrayList<>();
        for (int i = 0; i < sz; i++) {
            TreeNode n = q.poll();
            level.add(n.val);
            if (n.left != null) q.add(n.left);
            if (n.right != null) q.add(n.right);
        }
        res.add(level);
    }
    return res;
}

Time Complexity: O(n)
Space Complexity: O(n)

Question 5: detect cycle in linked list

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Problem Statement: Return true if the linked list has a cycle.

Example:

Input: 3→2→0→-4→(back to 2)
Output: true

Solution (Java):

public boolean hasCycle(ListNode head) {
    ListNode slow = head, fast = head;
    while (fast != null && fast.next != null) {
        slow = slow.next;
        fast = fast.next.next;
        if (slow == fast) return true;
    }
    return false;
}

Time Complexity: O(n)
Space Complexity: O(1)

Question 6: valid parentheses

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Problem Statement: Given a string of brackets, determine if it is valid.

Example:

Input: "()[]{}"
Output: true

Solution (Java):

public boolean isValid(String s) {
    Deque<Character> st = new ArrayDeque<>();
    Map<Character, Character> pair = Map.of(')', '(', ']', '[', '}', '{');
    for (char c : s.toCharArray()) {
        if (pair.containsValue(c)) st.push(c);
        else if (st.isEmpty() || st.pop() != pair.get(c)) return false;
    }
    return st.isEmpty();
}

Time Complexity: O(n)
Space Complexity: O(n)

Question 7: reverse a string

Show solution

Problem Statement: Given a string, return it reversed.

Example:

Input: "placement"
Output: "tnemecalp"

Solution (Java):

public String reverse(String s) {
    return new StringBuilder(s).reverse().toString();
}

Time Complexity: O(n)
Space Complexity: O(n)

Question 8

Q8: Which normal form removes transitive dependency?

Solution:

1NF: atomic values. 2NF: no partial dependency. 3NF: no transitive dependency.

Answer: 3NF

Question 9

Q9: Which data structure uses FIFO order?

Solution:

FIFO = First In First Out → Queue. Stack is LIFO.

Answer: Queue

Question 10

Q10: Worst-case time complexity of quicksort is?

Solution:

Unbalanced partitions (already sorted with bad pivot) → O(n²).

Answer: O(n²)

Question 11

Q11: Which protocol is connection-oriented at the transport layer?

Solution:

TCP is connection-oriented; UDP is connectionless.

Answer: TCP

Key insights from 2025 Unacademy Online Assessment

Coding Section is Critical: Must solve 2-3 coding problems correctly to advance
Learning Platform Focus: Strong emphasis on video streaming systems, course recommendations, learning platform architecture
Time Management: 2-3 problems in 90 minutes requires excellent speed and accuracy
Success Rate: Only 10-15% cleared OA and advanced to interviews
Platform: Unacademy assessment platform or HackerRank
Focus Areas: Arrays, trees, graphs, dynamic programming, learning platform systems, course recommendations
Enhanced Emphasis: Optimal solutions, learning platform architecture, and course recommendation systems

Unacademy 2025 interview experiences

Based on recent candidate experiences from 2025 Unacademy interviews:

2025 Interview Process:

Online Assessment (90 minutes): 2-3 coding problems
Technical Phone Screen (45-60 minutes): Coding problems, algorithm discussions, video streaming concepts, course recommendations
Onsite/Virtual Interviews (4-5 rounds, 45-60 minutes each):

Coding rounds (2-3): Algorithms, data structures, problem-solving
System Design rounds: Learning platform architecture, video streaming platforms, course recommendation systems, live classes
Behavioral rounds: Problem-solving approach, education passion, impact

2025 Interview Trends:

Increased emphasis on learning platform architecture and course recommendation systems
More focus on optimal solutions and modern ed-tech technologies
Enhanced behavioral questions about innovation and education passion
Questions about learning platform architecture and course recommendations

Common 2025 Interview Topics:

Coding: Arrays, strings, trees, graphs, dynamic programming, course recommendation algorithms
System Design: Learning platform architecture, video streaming platforms, course recommendation systems, live classes
Behavioral: Problem-solving, education passion, teamwork, impact
Unacademy Technologies: Learning platform architecture, video streaming platforms, course recommendation systems, live classes

Success Tips:

Strong coding performance is essential - solve problems optimally
Understand video streaming concepts, learning platform architecture, and course recommendation systems
Practice system design for learning platform architecture and course recommendation systems
Prepare examples demonstrating problem-solving and education passion
Learn Unacademy’s products and learning platform technologies
Practice explaining your thought process clearly

For detailed interview experiences from 2025, visit Unacademy Interview Experience page.

Preparation tips for Unacademy 2025 pattern

Master Coding Fundamentals: Focus on solving 2-3 coding problems correctly - arrays, trees, graphs, DP
Learning Platform Expertise: Strong understanding of learning platform architecture, video streaming systems, course recommendation systems
Practice Previous Year Papers: Solve Unacademy OA papers from 2020-2025 to understand evolving patterns
Time Management: Practice completing 2-3 coding problems in 90 minutes
LeetCode Practice: Solve 200+ LeetCode problems focusing on arrays, strings, trees, graphs (medium-hard difficulty)
Video Streaming Focus: Practice problems related to video streaming systems and course recommendations
System Design Mastery: Learn learning platform architecture design, video streaming platforms, course recommendation systems
Unacademy Technologies: Learn learning platform architecture, video streaming platforms, course recommendation systems, live classes
Behavioral Preparation: Prepare examples using STAR format - problem-solving, education passion, impact
Mock Tests: Take timed practice tests to improve speed and accuracy

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Unacademy Placement Papers 2025

Overview

Unacademy Online Assessment 2025 pattern

Unacademy Placement Papers 2025 - actual questions & solutions

Question 1: first non-repeating character

Question 2: rotate array right by k

Question 3: two sum

Question 4: binary tree level order

Question 5: detect cycle in linked list

Question 6: valid parentheses

Question 7: reverse a string

Question 8

Question 9

Question 10

Question 11

Key insights from 2025 Unacademy Online Assessment

Unacademy 2025 interview experiences

Preparation tips for Unacademy 2025 pattern

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