possen

//
// Description: Example implementation similar to NSNotificationCenter
// Language: Swift 2.1
// Date: November 7, 2015
//
// Author: Paul Ossenbruggen
//
// should support multiple threads by serializing access.
//
// allows posting to observers for a particular key where all blocks will get

possen

// Description: Implementation of a Trie
//
// Language: Swift 2.1
// Author: Paul Ossenbruggen
// Nov 7, 2015

import Foundation

class Trie  {
    var last : Bool = false

possen

//
// Description Switch problem in Swift solution
//
// Author: Paul Ossenbruggen
// Date: Nov 8, 2015
// Language: Swift 2.1
// See comment below for problem statement. This solves the second version where we don't know the state
// of the switch at the beginning.
//

possen

//
// Description Silly Hat village in Swift solution
//
// Author: Paul Ossenbruggen
// Date: Nov 8, 2015
// Language: Swift 2.1
// See comment below for problem statement.
//

import Foundation

possen

import Foundation

//
// Description; Various solutions for finding number change possibilities and minimum number of change possibilitis.
//
// Author: Paul Ossenbruggen
// Date: Nov 8, 2015
// Updated: June 8, 2020
// Language: Swift 5.3
// See comments below for problem statement.

possen

//
// Description: Finds the sum of all elements that add up to the target value using dynamic programming.
// Note: input array must be non negative and constrained to a reasonable ranage because it uses target+1 memory 
//
// Language: Swift
//
// Author: Paul Ossenbruggen
// Date: Nov 10, 2015
//

possen

//
// Description: Shortest distance graph. Calculates the distances from a start node to any node in the graph.
// Date: Nov 18, 2015
//
// Language: Swift
//
// Author: Paul Ossenbruggen
//
struct Edge : Equatable, Hashable, CustomStringConvertible {
    let weight : Int

possen

//
// Description: RandomArrays: pick randomly to build new array in two different ways. One a shuffle the other 
// picking from the array. Shuffle uses Fischer-Yates algorithm to generate uniform randomness. Allthough it 
// might be better to use Apple's Game kit function GKRandomSource.sharedRandom().arrayByShufflingObjectsInArray(array)
// if available in the OS release. Also this only works on arrays, if you want to shuffle any colletion type 
// it is possible to extend MutableCollectionType. 
//
// Author: Paul Ossenbruggen
//
// Date: Nov 20, 2015

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// 
// Description: Single Riffle detection, try to detct if a deck of cards has been riffled only once. 
//
// Language: Swift 2.1 (playground)
// Author: Paul Ossenbruggen
// Date: Nov 21, 2015
//
// Uses a stack approach because it is easy to get the next element. It could be done with iterators too which 
// be non destructive and might be faster, since swift copies the array a distructive approach should work. 
// 

possen

// 
// Anagram finder.
//
// Description: takes a list of anagrams and outputs the words in the same order as they appear in original string.
// Also outputs all the matched words after that in the order they appear after that.
//
// Language: Swift 5
// Author: Paul Ossenbruggen
// Date: Dec 4, 2015
//