Common algorithm implementation methods in Java language

The Java language is one of the most widely used programming languages ​​and is widely used in the computer field. In Java, algorithms are a very important concept. From the initial sorting algorithm to the implementation of data structures and algorithms, some common methods of the Java language are involved.

This article will focus on explaining common algorithm implementation methods in the Java language, including sorting algorithms, search algorithms, string matching algorithms, and tree structure processing methods, so that beginners can better master the algorithms of the Java language. accomplish.

1. Sorting Algorithm

Sorting algorithm is a very important concept in the computer field. It is the process of arranging a set of disordered data in order. In Java, commonly used sorting algorithms include selection sort, insertion sort, bubble sort, Hill sort, merge sort, quick sort, etc.

Selection sort: Selection sort is a simple, common and unstable sorting algorithm. Its idea is to select the minimum value each time and then exchange it with the corresponding position to gradually form an ordered sequence.

Insertion sort: Insertion sort is a stable sorting algorithm. The idea is to divide the data elements into sorted and unsorted parts, and gradually insert the unsorted data elements into the already sorted parts. in the appropriate position of sorting.

Bubble sorting: Bubble sorting is a simple and common sorting algorithm. Its idea is to compare adjacent data elements pairwise and exchange positions, gradually moving larger elements backward.

Hill sort: Hill sort is an upgraded version of insertion sort. It is an efficient sorting algorithm. It uses grouping to sort, thus avoiding the defects of insertion sort when processing large-scale data.

Merge sort: Merge sort is a stable and efficient sorting algorithm. It divides the data sequence into two parts for sorting, and then merges these ordered sequences to finally form a complete ordered sequence. .

Quick sort: Quick sort is an efficient and common sorting algorithm. Its idea is to divide the data sequence into left and right parts, and then perform a gradually narrowing recursive operation on the left and right parts to form a sequence sequence.

2. Search algorithm

The search algorithm is an algorithm used to find target elements in a data collection. In Java, common search algorithms include linear search, binary search, breadth-first search, depth-first search, etc.

Linear search: Linear search is also called sequential search. It is a search method that scans one by one from front to back. It is suitable for situations where the data set is small or disordered.

Binary search: Binary search is also called half search. It is an algorithm that uses the ordered nature of data sets to search. The search efficiency is very high, but the order of the data set needs to be ensured.

Breadth-first search: Breadth-first search is an algorithm that uses the data structure of a queue to search. Its core idea is to start from the initial state and traverse the entire state space layer by layer until the target state is found.

Depth-first search: Depth-first search is an algorithm that uses the data structure of the stack to search. Its core idea is to start from the initial state and search in depth layer by layer until it can no longer be searched.

3. String Matching Algorithm

The string matching algorithm is a computer algorithm that searches for the existence of another string in a string. It is used in many places, such as password matching. wait. In Java, commonly used string matching algorithms include Brute-Force algorithm, KMP algorithm, Boyer-Moore algorithm, etc.

Brute-Force algorithm: The Brute-Force algorithm is also called a brute force matching algorithm. Its idea is to compare the target string with the pattern string one by one until a match is found.

KMP algorithm: The KMP algorithm is an efficient string matching algorithm. Its core idea is to maintain a next array to indicate the next matching position after a match fails, thereby reducing the number of comparisons.

Boyer-Moore algorithm: Boyer-Moore algorithm is a common and efficient string matching algorithm. Its core idea is to compare pattern strings from back to front, thereby quickly eliminating unmatched character combinations .

4. How to deal with tree structures

Tree structure is a very important concept in computer science, and its applications are widely used in computer science, biology, engineering and other fields. In Java, commonly used methods for processing tree structures include pre-, mid-, and post-order traversal, hierarchical traversal, maximum depth of the tree, diameter of the tree, etc.

Pre-, mid-, and post-order traversal: Pre-, mid-, and post-order traversal is a very common traversal method for tree structures and is very common in practical applications. Pre-order, mid-order and post-order traversal refers to the traversal method of traversing the root node, intermediate nodes and subsequent nodes first.

Hierarchical traversal: Hierarchical traversal is a special traversal method of tree structure. Its core idea is to traverse in a hierarchical manner to obtain the relationship between child nodes and parent nodes.

The maximum depth of the tree: The maximum depth of the tree refers to the length of the longest path from the root node to the leaves. Its calculation method is often implemented by recursive methods.

Diameter of tree: The diameter of tree refers to the longest distance between any two nodes in the tree. Its calculation method can also be implemented recursively, that is, the maximum diameter in the subtree of each node is calculated.

Summarize

There are many common algorithm implementation methods in the Java language, involving sorting algorithms, search algorithms, string matching algorithms, and tree structure processing methods. This article mainly introduces common algorithm implementation methods in the Java language, as well as related concepts and applications. Beginners can better master the algorithm implementation in Java language by learning the methods introduced in this article.

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