Q3 & Q4 Problems from Recent 34 Contests for OA Preparation

One of the most effective ways to prepare for online assessments is to practice the third and fourth questions from recent LeetCode contests, as these problems closely match the difficulty level and patterns commonly seen in actual OA rounds at top tech companies.

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Below is a curated list of Q3 and Q4 problems from the most recent Weekly and Biweekly contests.

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Contest Problems

Weekly Contest 487

• Q3: Design Ride Sharing System
• Q4: Longest Alternating Subarray After Removing At Most One Element

Biweekly Contest 175

• Q3: Longest Strictly Increasing Subsequence With Non-Zero Bitwise AND
• Q4: Minimum Partition Score

Weekly Contest 486

• Q3: Pythagorean Distance Nodes in a Tree
• Q4: Find Nth Smallest Integer With K One Bits

Weekly Contest 485

• Q3: Design Auction System
• Q4: Lexicographically Smallest String After Deleting Duplicate Characters

Biweekly Contest 174

• Q3: Number of Alternating XOR Partitions
• Q4: Minimum Edge Toggles on a Tree

Weekly Contest 484

• Q3: Count Caesar Cipher Pairs
• Q4: Maximum Bitwise AND After Increment Operations

Weekly Contest 483

• Q3: Minimum Cost to Make Two Binary Strings Equal
• Q4: Minimum Cost to Merge Sorted Lists

Biweekly Contest 173

• Q3: Find Maximum Value in a Constrained Sequence
• Q4: Count Routes to Climb a Rectangular Grid

Weekly Contest 482

• Q3: Smallest All-Ones Multiple
• Q4: Number of Balanced Integers in a Range

Weekly Contest 481

• Q3: Minimum Swaps to Avoid Forbidden Values
• Q4: Total Sum of Interaction Cost in Tree Groups

Biweekly Contest 172

• Q3: Maximum Score After Binary Swaps
• Q4: Last Remaining Integer After Deletion

Weekly Contest 480

• Q3: Minimum Moves to Balance Circular Array
• Q4: Minimum Deletions to Make Alternating Substring

Weekly Contest 479

• Q3: Total Score of Dungeon Runs
• Q4: Maximum Subgraph Score in a Tree

Biweekly Contest 171

• Q3: Maximize Points After Choosing K Tasks
• Q4: Minimum Inversion Count in Subarrays

Weekly Contest 478

• Q3: Minimum Absolute Distance Between Mirror Pairs
• Q4: Minimum Operations to Equalize Subarrays

Weekly Contest 477

• Q3: Concatenate Non-Zero Digits and Multiply II
• Q4: Number of Effective Subsequences

Biweekly Contest 170

• Q3: Lexicographically Smallest Negated Permutation
• Q4: Total Waviness of Numbers in Range II

Weekly Contest 476

• Q3: Count Distinct Integers After Removing Zeros
• Q4: Count Stable Subarrays

Weekly Contest 475

• Q3: Maximum Path Score in a Grid
• Q4: Maximize Cyclic Partition Score

Biweekly Contest 169

• Q3: Longest Non-Decreasing Subarray After Replacing at Most One Element
• Q4: Count Subarrays With Majority Element II

Weekly Contest 474

• Q3: Minimum Time to Complete All Deliveries
• Q4: Lexicographically Smallest Palindromic Permutation

Weekly Contest 473

• Q3: Stable Subarrays With Equal Boundary Sum
• Q4: Count Distinct Subarrays Divisible by K

Biweekly Contest 168

• Q3: Minimum Operations to Transform Array
• Q4: Count Ways to Choose Coprime Integers

Weekly Contest 472

• Q3: Lexicographically Smallest Permutation Greater Than Target
• Q4: Longest Balanced Subarray II

Weekly Contest 471

• Q3: Longest Balanced Substring II
• Q4: Sum of Perfect Square Ancestors

Biweekly Contest 167

• Q3: Design Exam Scores Tracker
• Q4: Maximum Partition Factor

Weekly Contest 470

• Q3: Remove K-Balanced Substrings
• Q4: Count No-Zero Pairs That Sum to N

Weekly Contest 469

• Q3: Number of ZigZag Arrays I
• Q4: Number of ZigZag Arrays II

Biweekly Contest 166

• Q3: Distinct Points Reachable After Removal
• Q4: Maximize Alternating Sum Using Swaps

Weekly Contest 468

• Q3: Split and Merge Array Transformation
• Q4: Maximum Total Subarray Value II

Weekly Contest 467

• Q3: Subsequence Sum After Capping Elements
• Q4: Number of Stable Subsequences

Biweekly Contest 165

• Q3: Generate Schedule
• Q4: Maximum XOR of Subsequences

Weekly Contest 466

• Q3: Count Bowl Subarrays
• Q4: Count Binary Palindromic Numbers

Weekly Contest 465

• Q3: Max Product of Two Integers (No Common Bits)
• Q4: Sum of Beautiful Subsequences

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Why These Problems Matter

These Q3 and Q4 problems are particularly valuable for OA preparation because they:

• Match OA Difficulty: Most online assessments feature problems at this exact difficulty level
• Test Multiple Concepts: They often combine multiple data structures and algorithms
• Require Optimization: You need to think beyond brute force solutions
• Build Problem-Solving Speed: Regular practice helps you recognize patterns faster
• Simulate Real Conditions: Contest timing mirrors actual OA time constraints

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Final Thoughts

Consistent practice with these contest problems will significantly improve your performance in online assessments. Remember that the goal isn't just to solve problems, but to develop pattern recognition and problem-solving intuition.

Let's connect on LinkedIn - I regularly share interview tips, problem-solving strategies, and coding resources that can help accelerate your preparation!

Good luck with your OA preparation!