Code Challenges

Get better at coding with practice problems.

Coding Challenges

Select a problem, write code, run test cases, and submit your solution.

Start with beginner challenges

Array Matrix Breadth First Search

Intermediate

Implement the `rotateImageClockwise` method that returns the matrix after rotating it 90 degrees clockwise.

Array Matrix Breadth First Search

Intermediate

Implement the `spiralOrderTraversalLength` method that returns the number of elements visited in spiral order.

Array Matrix Breadth First Search

Intermediate

Implement the `setMatrixZeroesCount` method that counts cells affected after applying matrix zeroing rules.

Array Sorting Greedy

Intermediate

Implement the `maximumUnitsTruck` method that returns the maximum units that can be loaded onto the truck.

Array Sorting Greedy

Intermediate

Implement the `reconstructQueueCount` method that returns the number of people after reconstructing the queue.

Array Sorting Greedy

Intermediate

Implement the `partitionLabelsNumber` method that returns how many partitions can be made so each character appears in one part.

Array Sorting Greedy

Learner

Implement the `assignCookiesMaximumChildren` method that returns the maximum number of children that can receive a suitable cookie.

Array Sorting Greedy

Intermediate

Implement the `minimumArrowsBalloons` method that returns the minimum arrows needed to burst all balloons.

Array Sorting Greedy

Intermediate

Implement the `eraseOverlapIntervalsCount` method that returns how many intervals must be removed to avoid overlaps.

Array Sorting Greedy

Proficient

Implement the `candyDistributionMinimum` method that returns the minimum candies needed while respecting rating rules.

Array Sorting Greedy

Intermediate

Implement the `gasStationCircuitStart` method that returns the gas station index from which the full circuit can be completed.

Array Sorting Greedy

Intermediate

Implement the `jumpGameMinimumJumpsGreedy` method that returns the minimum number of jumps needed to reach the end.

Array Sorting Greedy

Learner

Implement the `jumpGameReachableGreedy` method that checks whether the last index is reachable using greedy logic.

Array String Hash Map Sliding Window

Intermediate

Implement the `countNiceSubarrays` method that counts subarrays that contain exactly k odd numbers.

Array String Hash Map Sliding Window

Intermediate

Implement the `longestSubarrayAfterDeletingOne` method that returns the longest subarray of 1 values after deleting one element.

Array String Hash Map Sliding Window

Intermediate

Implement the `fruitIntoBasketsMaxCount` method that returns the maximum fruits collected using at most two fruit types.

Array String Hash Map Sliding Window

Intermediate

Implement the `maxConsecutiveOnesWithKFlips` method that returns the longest run of 1 values after flipping at most k zeroes.

Array String Hash Map Sliding Window

Proficient

Implement the `longestRepeatingCharReplacement` method that returns the longest substring length after replacing at most k characters.

Array String Hash Map Sliding Window

Intermediate

Implement the `findAnagramStartCount` method that counts starting positions where an anagram of the pattern appears.