You can make use of Floyd’s cycle-finding algorithm, also known as tortoise and hare algorithm. The idea is to have two references to the list and move them at different speeds. Move one forward by 1 node and the other by 2 nodes. If the linked list has a loop they will definitely meet. Else … Read more
I’ve just put together what you may be looking for: http://www.graphdracula.net It’s JavaScript with directed graph layouting, SVG and you can even drag the nodes around. Still needs some tweaking, but is totally usable. You create nodes and edges easily with JavaScript code like this: var g = new Graph(); g.addEdge(“strawberry”, “cherry”); g.addEdge(“cherry”, “apple”); g.addEdge(“id34”, … Read more
Here’s an explanation in layman’s terms. Let’s assume you want to fill up a library with books and not just stuff them in there, but you want to be able to easily find them again when you need them. So, you decide that if the person that wants to read a book knows the title … Read more
Here: public class Tree<T> { private Node<T> root; public Tree(T rootData) { root = new Node<T>(); root.data = rootData; root.children = new ArrayList<Node<T>>(); } public static class Node<T> { private T data; private Node<T> parent; private List<Node<T>> children; } } That is a basic tree structure that can be used for String or any other … Read more
Hash‘s key? method tells you whether a given key is present or not. session.key?(“user”)
Tries, also known as prefix-trees or crit-bit trees, have existed for over 40 years but are still relatively unknown. A very cool use of tries is described in “TRASH – A dynamic LC-trie and hash data structure”, which combines a trie with a hash function.
var stack = []; stack.push(2); // stack is now [2] stack.push(5); // stack is now [2, 5] var i = stack.pop(); // stack is now [2] alert(i); // displays 5 var queue = []; queue.push(2); // queue is now [2] queue.push(5); // queue is now [2, 5] var i = queue.shift(); // queue is now … Read more
Use a combination of Array.prototype.filter and Array.prototype.includes: const filteredArray = array1.filter(value => array2.includes(value)); For older browsers, with Array.prototype.indexOf and without an arrow function: var filteredArray = array1.filter(function(n) { return array2.indexOf(n) !== -1; }); NB! Both .includes and .indexOf internally compares elements in the array by using ===, so if the array contains objects it will … Read more
The following is an attempt to describe the Ukkonen algorithm by first showing what it does when the string is simple (i.e. does not contain any repeated characters), and then extending it to the full algorithm. First, a few preliminary statements. What we are building, is basically like a search trie. So there is a … Read more
For what it’s worth, a Dictionary is (conceptually) a hash table. If you meant “why do we use the Dictionary<TKey, TValue> class instead of the Hashtable class?”, then it’s an easy answer: Dictionary<TKey, TValue> is a generic type, Hashtable is not. That means you get type safety with Dictionary<TKey, TValue>, because you can’t insert any … Read more