What is Huffman coding? Huffman coding is a compression algorithm that assigns shorter binary codes to more frequent characters in an input string, optimizing data size. Huffman decoding is to recover the original text from the binary code generated from the huffman coding process. Using the Huffman algorithm, we compress …
In mathematics expressions, there are infix, prefix and postfix notations. Infix notation is characterized by the placement of operators between operands. For example, the plus sign in 2 + 2. Prefix notation is a notation in which operators precede their operands, such as + 3 4. Postfix notation is a …
An adjacency matrix is a 2d array representing a graph. The nodes are the headings for the rows and columns. The element in the cell indicates whether an edge is present between two nodes. Depth first search (DFS) is an algorithm used to traverse or search in a graph. The …
Autocomplete is a feature that search box returns the suggestions based on what you have typed. Autocomplete with trie provides an implementation of auto-complete by using data structure trie. A trie is a tree-like data structure in which every node stores a character. After building the trie, strings or substrings …
Dijkstra’s algorithm is an algorithm to find the shortest paths between vertices in a graph. It uses greedy technique by picking the un-visited vertex with the lowest distance. When all vertices have been evaluated, the result is the shortest path. This post provides code to find shortest path and second …
The K closest problem is to find K closest points to the pointer(0,0) (it is called center or origin). The input k is to specify how many points you should return. The Euclidean distance formula is √[ (x2–x1)^2 + (y2–y1)^2]. For this question, we don’t need to calculate the actual …
Shortest path in matrix is to find the shortest distance from the the source to the destination. As you know, graph can be represented as adjacent matrix. Therefore, we can use the Breadth First Search algorithm in graph to solve this problem. BFS starts from the source node. It explores …
A graph is a data structure that consists of a set of nodes (vertices) connected by edges. A graph is cyclic if the graph comprises a path that starts from a node and ends at the same node. In this post, a simplified solution is provided to detect cycle and …
To find number of possible combinations of valid parentheses, we have to know Catalan number. Catalan numbers are a sequence of natural numbers that follow the formula showing below. The first few Catalan numbers for n = 0, 1, 2, 3, 4, 5 … Cn = 1, 1, 2, 5, …
Build hierarchy tree is to build a corporation hierarchy tree from an employ list. HashMap plays important role to store the data when reading the input. You can get the root by finding the employee without the manager. Starting from the root, get subordinates for each employee. Then you build …
