12 KiB
알고리즘 - 자바
이 개발브런치는 기존 프로젝트를 Java 프로젝트 구조로 재개발하기 위해 작성되었다. 기여도를 위해 개발 지사로 전환할 수 있다. 자세한 내용은 이 문제를 참조하십시오. 컨트리뷰션을 위해 개발브런치로 전환할 수 있다. 자세한 내용은 이 이슈를 참고하십시오.
자바로 구현된 모든 알고리즘들 (교육용)
이것들은 단지 시범을 위한 것이다. 표준 자바 라이브러리에는 성능상의 이유로 더 나은 것들이 구현되어있다
정렬 알고리즘
Bubble(버블 소트)
From Wikipedia: 버블 소트(sinking sor라고도 불리움)는 리스트를 반복적인 단계로 접근하여 정렬한다. 각각의 짝을 비교하며, 순서가 잘못된 경우 그접한 아이템들을 스왑하는 알고리즘이다. 더 이상 스왑할 것이 없을 때까지 반복하며, 반복이 끝남음 리스트가 정렬되었음을 의미한다.
속성
- 최악의 성능 O(n^2)
- 최고의 성능 O(n)
- 평균 성능 O(n^2)
View the algorithm in action
Insertion
From Wikipedia: Insertion sort is a simple sorting algorithm that builds the final sorted array (or list) one item at a time. It is much less efficient on large lists than more advanced algorithms such as quicksort, heapsort, or merge sort. In the figure, each bar represents an element of an array that needs to be sorted. What happens at the first intersection of the top most and second top most bars is to swap these elements, represented by bars, because the second element has a higher precedence than the first element does. By repeating this method, insertion sort completes sorting.
Properties
- Worst case performance O(n^2)
- Best case performance O(n)
- Average case performance O(n^2)
View the algorithm in action
Merge
From Wikipedia: In computer science, merge sort (also commonly spelt mergesort) is an efficient, general-purpose, comparison-based sorting algorithm. Most implementations produce a stable sort, which means that the implementation preserves the input order of equal elements in the sorted output. Mergesort is a divide and conquer algorithm that was invented by John von Neumann in 1945.
Properties
- Worst case performance O(n log n) (typical)
- Best case performance O(n log n)
- Average case performance O(n log n)
View the algorithm in action
Quick
From Wikipedia: Quicksort (sometimes called partition-exchange sort) is an efficient sorting algorithm, serving as a systematic method for placing the elements of an array in order.
Properties
- Worst case performance O(n^2)
- Best case performance O(n log n) or O(n) with three-way partition
- Average case performance O(n log n)
View the algorithm in action
Selection
From Wikipedia: The algorithm divides the input list into two parts: the sublist of items already sorted, which is built up from left to right at the front (left) of the list, and the sublist of items remaining to be sorted that occupy the rest of the list. Initially, the sorted sublist is empty and the unsorted sublist is the entire input list. The algorithm proceeds by finding the smallest (or largest, depending on sorting order) element in the unsorted sublist, exchanging (swapping) it with the leftmost unsorted element (putting it in sorted order), and moving the sublist boundaries one element to the right.
Properties
- Worst case performance O(n^2)
- Best case performance O(n^2)
- Average case performance O(n^2)
View the algorithm in action
Shell
From Wikipedia: Shellsort is a generalization of insertion sort that allows the exchange of items that are far apart. The idea is to arrange the list of elements so that, starting anywhere, considering every nth element gives a sorted list. Such a list is said to be h-sorted. Equivalently, it can be thought of as h interleaved lists, each individually sorted.
Properties
- Worst case performance O(nlog2 2n)
- Best case performance O(n log n)
- Average case performance depends on gap sequence
View the algorithm in action
Time-Compexity Graphs
Comparing the complexity of sorting algorithms (Bubble Sort, Insertion Sort, Selection Sort)
Search Algorithms
Linear
From Wikipedia: linear search or sequential search is a method for finding a target value within a list. It sequentially checks each element of the list for the target value until a match is found or until all the elements have been searched. The linear search runs in at the worst linear time and makes at most n comparisons, where n is the length of the list.
Properties
- Worst case performance O(n)
- Best case performance O(1)
- Average case performance O(n)
- Worst case space complexity O(1) iterative
Binary
From Wikipedia: Binary search, also known as half-interval search or logarithmic search, is a search algorithm that finds the position of a target value within a sorted array. It compares the target value to the middle element of the array; if they are unequal, the half in which the target cannot lie is eliminated and the search continues on the remaining half until it is successful.
Properties
- Worst case performance O(log n)
- Best case performance O(1)
- Average case performance O(log n)
- Worst case space complexity O(1)
From Wikipedia: Shellsort is a generalization of insertion sort that allows the exchange of items that are far apart. The idea is to arrange the list of elements so that, starting anywhere, considering every nth element gives a sorted list. Such a list is said to be h-sorted. Equivalently, it can be thought of as h interleaved lists, each individually sorted.
Properties
- Worst case performance O(nlog2 2n)
- Best case performance O(n log n)
- Average case performance depends on gap sequence
View the algorithm in action
Links to the rest of the algorithms
| Conversions | Dynamic Programming | Ciphers | Miscellaneous |
|---|---|---|---|
| Any Base to Any Base | Coin Change | Caesar | Heap Sort |
| Any Base to Decimal | Egg Dropping | Columnar Transposition Cipher | Palindromic Prime Checker |
| Binary to Decimal | Fibonacci | RSA | More soon... |
| Binary to HexaDecimal | Kadane Algorithm | more coming soon... | |
| Binary to Octal | Knapsack | ||
| Decimal To Any Base | Longest Common Subsequence | ||
| Decimal To Binary | Longest Increasing Subsequence | ||
| Decimal To Hexadecimal | Rod Cutting | ||
| and much more... | and more... |
Data Structures
| Graphs | Heaps | Lists | Queues |
|---|---|---|---|
| BFS | Empty Heap Exception | Circle Linked List | Generic Array List Queue |
| DFS | Heap | Doubly Linked List | Queues |
| Graphs | Heap Element | Singly Linked List | |
| Kruskals Algorithm | Max Heap | ||
| Matrix Graphs | Min Heap | ||
| PrimMST |
| Stacks | Trees |
|---|---|
| Node Stack | AVL Tree |
| Stack of Linked List | Binary Tree |
| Stacks | And much more... |