A collection of LeetCode novel solutions that is implemented in Java. It would support you to solve the problems from easy to hard by the simplest ways.
# | Problem | Difficulty | Source code | Solution |
---|---|---|---|---|
1 | Two Sum | Medium | Java | 1. Hash O(n) and O(n) space. 2. Sort and search with two points O(n) and O(1) space. |
2 | Add Two Numbers | Medium | Java | Take care of the carry from lower digit. |
--- | To-be-updated soon | ---------- | ----------- | -------- |
Below are the Big O performance of common functions of different Java Collections.
List | Add | Remove | Get | Contains | Next | Data Structure |
---|---|---|---|---|---|---|
ArrayList | O(1) | O(n) | O(1) | O(n) | O(1) | Array |
LinkedList | O(1) | O(1) | O(n) | O(n) | O(1) | Linked List |
Set | Add | Remove | Contains | Next | Size | Data Structure |
---|---|---|---|---|---|---|
HashSet | O(1) | O(1) | O(1) | O(h/n) | O(1) | Hash Table |
LinkedHashSet | O(1) | O(1) | O(1) | O(1) | O(1) | Hash Table + Linked List |
EnumSet | O(1) | O(1) | O(1) | O(1) | O(1) | Bit Vector |
TreeSet | O(log n) | O(log n) | O(log n) | O(log n) | O(1) | Red-black tree |
ConcurrentSkipListSet | O(log n) | O(log n) | O(log n) | O(1) | O(n) | Skip List |
- Note: h is the table capacity
Queue | Offer | Peak | Poll | Remove | Size | Data Structure |
---|---|---|---|---|---|---|
PriorityQueue | O(log n) | O(1) | O(log n) | O(n) | O(1) | Priority Heap |
LinkedList | O(1) | O(1) | O(1) | O(1) | O(1) | Array |
ArrayDequeue | O(1) | O(1) | O(1) | O(n) | O(1) | Linked List |
ConcurrentLinkedQueue | O(1) | O(1) | O(1) | O(n) | O(n) | Linked List |
ArrayBlockingQueue | O(1) | O(1) | O(1) | O(n) | O(1) | Array |
PriorirityBlockingQueue | O(log n) | O(1) | O(log n) | O(n) | O(1) | Priority Heap |
SynchronousQueue | O(1) | O(1) | O(1) | O(n) | O(1) | None! |
DelayQueue | O(log n) | O(1) | O(log n) | O(n) | O(1) | Priority Heap |
LinkedBlockingQueue | O(1) | O(1) | O(1) | O(n) | O(1) | Linked List |
Map | Get | ContainsKey | Next | Data Structure |
---|---|---|---|---|
HashMap | O(1) | O(1) | O(h / n) | Hash Table |
LinkedHashMap | O(1) | O(1) | O(1) | Hash Table + Linked List |
IdentityHashMap | O(1) | O(1) | O(h / n) | Array |
WeakHashMap | O(1) | O(1) | O(h / n) | Hash Table |
EnumMap | O(1) | O(1) | O(1) | Array |
TreeMap | O(log n) | O(log n) | O(log n) | Red-black tree |
ConcurrentHashMap | O(1) | O(1) | O(h / n) | Hash Tables |
ConcurrentSkipListMap | O(log n) | O(log n) | O(1) | Skip List |
Source: Suryaprakash R.
Source: MCN Professionals
Hieu Tran (trantrunghieu7492@gmail.com)