| Title | Topics | Action | |||
|---|---|---|---|---|---|
| 411 | Push a Value onto an Array StackAn array-backed stack stores its values in an int array and keeps `top` as the i... | easy | ○ Not Started | Data Structures & AlgorithmsStacks | Solve |
| 412 | Pop and Peek on an Array StackThe array stack can already push and display itself. The two ways of reading the... | easy | ○ Not Started | Data Structures & AlgorithmsStacks | Solve |
| 413 | Is the Array Stack Empty or Full?push, pop and peek all lean on two tiny status methods, and both of them are mis... | easy | ○ Not Started | Data Structures & AlgorithmsStacks | Solve |
| 414 | Display an Array Stack Bottom to TopThe stack works, but printing one shows nothing useful. Build the text yourself ... | easy | ○ Not Started | Data Structures & AlgorithmsStacks | Solve |
| 415 | Push onto a Linked-Node StackThis stack has no array and no capacity - it is a chain of nodes, and the field ... | easy | ○ Not Started | Data Structures & AlgorithmsStacks | Solve |
| 416 | Push and Pop a Generic StackMyStack<T> holds any type by storing the values in an Object array. The pop() th... | easy | ○ Not Started | Data Structures & AlgorithmsStacks | Solve |
| 417 | Enqueue Into an Array QueueShiftQueue stores its values in a plain array and always keeps the front at inde... | easy | ○ Not Started | Data Structures & AlgorithmsQueues | Solve |
| 418 | Dequeue by Shifting LeftShiftQueue keeps the front of the queue at index 0, so removing it means sliding... | easy | ○ Not Started | Data Structures & AlgorithmsQueues | Solve |
| 419 | Enqueue With WraparoundCircularQueue never shifts. It tracks where the queue starts (front) and how man... | easy | ○ Not Started | Data Structures & AlgorithmsQueues | Solve |
| 420 | Dequeue From a Circular QueueCircularQueue removes a value by moving front forward instead of shifting the wh... | easy | ○ Not Started | Data Structures & AlgorithmsQueues | Solve |
| 421 | Enqueue at the Tail of a Linked QueueLinkedQueue adds at the tail and removes at the head, so it tracks both ends. Ev... | easy | ○ Not Started | Data Structures & AlgorithmsQueues | Solve |
| 422 | Peek at the Front of a Linked QueueLinkedQueue is complete except for peek(), the method that looks at the front of... | easy | ○ Not Started | Data Structures & AlgorithmsQueues | Solve |
| 423 | Transfer One Stack Into the OtherStackQueue fakes a queue out of two stacks: enqueue pushes onto inbox, while deq... | easy | ○ Not Started | Data Structures & AlgorithmsQueues | Solve |
| 424 | Serve the Print QueuePrintQueue holds waiting job names in a java.util.Queue so the printer serves th... | easy | ○ Not Started | Data Structures & AlgorithmsQueues | Solve |
| 425 | Add a Node to the FrontAn IntList keeps its nodes in a chain that starts at head. Inserting at the fron... | easy | ○ Not Started | Data Structures & AlgorithmsLinked Lists | Solve |
| 426 | Add a Node to the EndaddFirst() is already written for you. Appending is the expensive twin: with no ... | easy | ○ Not Started | Data Structures & AlgorithmsLinked Lists | Solve |
| 427 | Remove the First NodeUnlinking the head node is the mirror image of addFirst(): read the value out, t... | easy | ○ Not Started | Data Structures & AlgorithmsLinked Lists | Solve |
| 428 | Count the NodesThis IntList stores no counter, so size() has to find out the hard way: start a ... | easy | ○ Not Started | Data Structures & AlgorithmsLinked Lists | Solve |
| 429 | Find the Index of the Smallest ValueNumberList owns an int array and its size. A working selectionSort() is already ... | easy | ○ Not Started | Data Structures & AlgorithmsSorting | Solve |
| 430 | Finish the Bubble Sort Inner LoopNumberList owns an int array and its size. bubbleSort() already has both of its ... | easy | ○ Not Started | Data Structures & AlgorithmsSorting | Solve |
| 431 | Drop the Key Into Place (Insertion Sort)Insertion sort never swaps. It saves one value as key, shifts every larger value... | easy | ○ Not Started | Data Structures & AlgorithmsSorting | Solve |
| 432 | Finish the Binary Search Middle StepThis NumberList is built from values already in ascending order. binarySearch(in... | easy | ○ Not Started | Data Structures & AlgorithmsSorting | Solve |
| 433 | Add to the Front of a DequeArrayDequeInt holds up to 5 ints in a circular array. isEmpty, isFull, size, add... | easy | ○ Not Started | Data Structures & AlgorithmsDeques | Solve |
| 434 | Build the Array Stack CoreThe two fields are declared but nothing sets them up, so a new stack is unusable... | medium | ○ Not Started | Data Structures & AlgorithmsStacks | Solve |
| 435 | Finish the Linked-Node Stackpush and the display are written. The three methods that read or remove the fron... | medium | ○ Not Started | Data Structures & AlgorithmsStacks | Solve |
| 436 | Check for Balanced BracketsA stack is the classic way to check bracket nesting: an opener waits on the stac... | medium | ○ Not Started | Data Structures & AlgorithmsStacks | Solve |
| 437 | Track the Minimum With a Second StackMinStack keeps two stacks: `main` holds every value, and `mins` holds only the v... | medium | ○ Not Started | Data Structures & AlgorithmsStacks | Solve |
| 438 | Evaluate a Postfix ExpressionIn postfix notation the operator comes after its two operands, so `3 4 +` means ... | medium | ○ Not Started | Data Structures & AlgorithmsStacks | Solve |
| 439 | Guard an Empty Array QueueShiftQueue can already accept values and print itself, but nothing stops it read... | medium | ○ Not Started | Data Structures & AlgorithmsQueues | Solve |
| 440 | Build the Circular Queue CoreThis CircularQueue has its three fields declared but never set up, and both meth... | medium | ○ Not Started | Data Structures & AlgorithmsQueues | Solve |
| 441 | Circular Queue With front and rearRingQueue tracks front and rear instead of a size counter, which creates a probl... | medium | ○ Not Started | Data Structures & AlgorithmsQueues | Solve |
| 442 | Build Both Ends of a Linked QueueLinkedQueue adds at the tail and removes at the head, so the two missing methods... | medium | ○ Not Started | Data Structures & AlgorithmsQueues | Solve |
| 443 | Queue From Two StacksStackQueue must behave like a queue while owning nothing but two stacks. New val... | medium | ○ Not Started | Data Structures & AlgorithmsQueues | Solve |
| 444 | Find a Node by Index and by ValueA linked list has no random access, so both lookups are the same walk with a dif... | medium | ○ Not Started | Data Structures & AlgorithmsLinked Lists | Solve |
| 445 | Insert and Remove at a PositionBoth methods share one invariant: to change a link you must be standing on the n... | medium | ○ Not Started | Data Structures & AlgorithmsLinked Lists | Solve |
| 446 | Remove the First Node Holding a ValueUnlike a counted walk, this one stops on data you cannot predict, so carry two c... | medium | ○ Not Started | Data Structures & AlgorithmsLinked Lists | Solve |
| 447 | Keep the Tail Pointer HonestA TailedIntList holds head, tail and a size counter so that appending costs O(1)... | medium | ○ Not Started | Data Structures & AlgorithmsLinked Lists | Solve |
| 448 | Remove the Last NodeThe tail pointer hands you the last node instantly, but it does not save you her... | medium | ○ Not Started | Data Structures & AlgorithmsLinked Lists | Solve |
| 449 | Walk a Doubly Linked List Both WaysEvery DNode carries a prev as well as a next, so the same chain can be read from... | medium | ○ Not Started | Data Structures & AlgorithmsLinked Lists | Solve |
| 450 | Remove the Last Node of a Doubly Linked ListIn a singly linked list, removing the last node requires walking the chain to fi... | medium | ○ Not Started | Data Structures & AlgorithmsLinked Lists | Solve |
| 451 | Reverse the List In PlaceReversing means re-aiming every next pointer at the node behind it instead of bu... | medium | ○ Not Started | Data Structures & AlgorithmsLinked Lists | Solve |
| 452 | Find the Middle NodeYou could call size() and walk half of it, but one pass is enough: move slow one... | medium | ○ Not Started | Data Structures & AlgorithmsLinked Lists | Solve |
| 453 | Build Selection Sort From Its HelperNumberList gives you two finished helpers: findMinIndex(int start), which return... | medium | ○ Not Started | Data Structures & AlgorithmsSorting | Solve |
| 454 | Write Binary Search From ScratchThis NumberList is built from values that are already in ascending order, so it ... | medium | ○ Not Started | Data Structures & AlgorithmsSorting | Solve |
| 455 | Keep a List Sorted as You InsertSortedIntList stays in ascending order at all times, so there is no sort to run ... | medium | ○ Not Started | Data Structures & AlgorithmsSorting | Solve |
| 456 | Build Both Ends of a DequeA deque has four doors: add and remove at each end. Lock two of them and the sam... | medium | ○ Not Started | Data Structures & AlgorithmsDeques | Solve |