Code Challenges

Get better at coding with practice problems.

Coding Challenges

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

Two Pointers Linked List

Learner

Implement the `palindromeLinkedListCheck` method that checks whether the linked list values form a palindrome.

Two Pointers Linked List

Learner

Implement the `middleNodeLinkedList` method that returns the value stored at the middle node of the linked list.

Two Pointers Linked List

Intermediate

Implement the `removeNthNodeFromEnd` method that removes the nth node from the end and returns the updated list values.

Two Pointers Linked List

Learner

Implement the `mergeTwoSortedLinkedLists` method that merges two sorted linked lists and returns the sorted values.

Two Pointers Linked List

Intermediate

Implement the `detectCycleLinkedListValues` method that checks whether the linked list has a cycle at the given position.

Two Pointers Linked List

Learner

Implement the `reverseLinkedListInterview` method that returns linked list values after reversing the list.

Queue Deque Simulation

Learner

Implement the `movingAverageStreamLast` method that returns the last moving average value for a fixed-size window.

Queue Deque Simulation

Intermediate

Implement the `circularTourStartIndex` method that returns a starting petrol pump index that can complete the circular tour.

Queue Deque Simulation

Intermediate

Implement the `taskSchedulerIntervals` method that returns the minimum intervals required to schedule tasks with cooldown.

Queue Deque Simulation

Proficient

Implement the `shortestPathBinaryMatrixLength` method that returns the shortest path length through a binary matrix.

Queue Deque Simulation

Intermediate

Implement the `openLockMinimumTurnsSimple` method that returns the minimum turns needed to reach the lock target.

Queue Deque Simulation

Intermediate

Implement the `perfectSquaresBfsSteps` method that returns the minimum number of perfect squares that sum to n.

Queue Deque Simulation

Intermediate

Implement the `numberOfIslandsBfsCount` method that counts islands in a grid using breadth-first search.

Queue Deque Simulation

Intermediate

Implement the `rottingOrangesMinutes` method that returns the minutes required for all fresh oranges to rot.

Queue Deque Simulation

Intermediate

Implement the `firstNonRepeatingCharacterStream` method that returns the first non-repeating character after processing a stream.

Queue Deque Simulation

Proficient

Implement the `slidingWindowMaximumDeque` method that returns maximum values for every sliding window of size k.

Stack Topological Sort Simulation

Guru

Implement the `basicCalculatorPlusMinus` method that evaluates an expression containing plus and minus operations.

Stack Topological Sort Simulation

Intermediate

Implement the `onlineStockSpanLast` method that returns the latest stock span value from the price stream.

Stack Topological Sort Simulation

Intermediate

Implement the `removeKDigitsMinimum` method that removes k digits to form the smallest possible number.