public void GivenAQueueWith1And3Enqueued_WhenEnqueue2_ShouldEnqueueThisNewValueOnMiddle()
{
// Arrange
var queue = new MyPriorityQueue(3);
queue.Enqueue(1);
queue.Enqueue(3);
// Act
queue.Enqueue(2);
// Assert
queue.Dequeue().Should().Be(1);
queue.Dequeue().Should().Be(2);
queue.Dequeue().Should().Be(3);
}
public void GivenAQueueWithSomeItems_WhenTryToEnqueueANewValueThatIsGreaterThanAll_ShouldEnqueueThisLast()
{
// Arrange
var queue = new MyPriorityQueue(3);
queue.Enqueue(1);
queue.Enqueue(2);
// Act
queue.Enqueue(3);
// Assert
queue.Dequeue().Should().Be(1);
queue.Dequeue().Should().Be(2);
queue.Dequeue().Should().Be(3);
}
static void Main()
{
var people = new MyPriorityQueue <Person>();
people.Enqueue(new Person("Doncho", 25));
people.Enqueue(new Person("Niki", 24));
people.Enqueue(new Person("Ivo", 25));
people.Enqueue(new Person("Asya", 22));
people.Enqueue(new Person("Pesho", int.MinValue));
while (people.Count > 0)
{
Console.WriteLine(people.Dequeue());
}
}
public static void ShortestPath(SqlInt64 startNode, SqlInt64 endNode, SqlInt32 maxNodesToCheck, out SqlString pathResult, out SqlDouble distResult)
{
Dictionary <long, double> distance = new Dictionary <long, double>(); // curr shortest distance (double) from startNode to (key) node
Dictionary <long, long> previous = new Dictionary <long, long>(); // predecessor values to construct the actual path when done
Dictionary <long, bool> beenAdded = new Dictionary <long, bool>(); // has node been added to the queue yet? Once added, we don't want to add again
long startNodeAsLong = (long)startNode;
long endNodeAsLong = (long)endNode;
int maxNodesToCheckAsInt = (int)maxNodesToCheck;
MyPriorityQueue PQ = new MyPriorityQueue();
//initialize start node
distance[startNodeAsLong] = 0.0; // distance from start node to itself is 0
previous[startNodeAsLong] = -1; // -1 is the code for undefined.
PQ.Enqueue(new NodeDistance(startNodeAsLong, 0.0)); // the queue holds distance information because Enqueue and Dequeue need it to keep queue ordered by priority. alt approach would be to store only node IDs and then do a distance lookup
beenAdded[startNodeAsLong] = true;
double alt = 0.0; //'test distance'
try
{
while (PQ.Count() > 0 && beenAdded.Count < maxNodesToCheckAsInt)
{
NodeDistance u = PQ.Dequeue();// node with shortest distance from start
if (u.nodeID == endNode)
{
break;// found the target end node
}
//fetch all neighbors (v) of u
List <Tuple <long, double> > neighbors = new List <Tuple <long, double> >();
neighbors = FetchNeighbors(u.nodeID);
foreach (var v in neighbors) // if there are no neighbors, this loop will exit immediately
{
if (beenAdded.ContainsKey(v.Item1) == false) //first appearance of node v
{
distance[v.Item1] = double.MaxValue; //stand-in for infinity
previous[v.Item1] = -1; //undefined
PQ.Enqueue(new NodeDistance(v.Item1, double.MaxValue)); //maxValue is a dummy value
beenAdded[v.Item1] = true;
}
//alt = distance[u.nodeID] + 1.0; // if all edge weights are just hops can simplify to this
alt = distance[u.nodeID] + v.Item2; // alt = dist(start-to-u) + dist(u-to-v), so alt is total distance from start to v
if (alt < distance[v.Item1]) // is alt a new, shorter distance from start to v?
{
distance[v.Item1] = alt;
previous[v.Item1] = u.nodeID;
PQ.ChangePriority(v.Item1, alt); // this will change the distance/priority
}
}
}
// extract the shortest path as a string from the previous[] array
pathResult = "NOTREACHABLE"; // default result string
distResult = -1.0; // distance result defaults to -1 == unreachable
if (distance.ContainsKey(endNodeAsLong) == true) // endNode was encountered at some point in the algorithm
{
double sp = distance[endNodeAsLong]; // shortest path distance
if (sp != double.MaxValue) // we have a reachable path
{
pathResult = "";
long currNode = endNodeAsLong;
while (currNode != startNodeAsLong) // construct the path as semicolon delimited string
{
pathResult += currNode.ToString() + ";";
currNode = previous[currNode];
}
pathResult += startNode.ToString(); // tack on the start node
distResult = sp; // the distance result
}
}
}
catch (Exception ex) // typically Out Of Memory or a Command TimeOut
{
pathResult = ex.ToString();
distResult = -1.0;
}
}
static void Main()
{
/*Implement a class PriorityQueue<T> based on the data structure "binary heap".
Write a program to read a large collection of products(name + price) and efficiently find the first 20 products in the price range[a…b].
Test for 500 000 products and 10 000 price searches.
Hint: you may use OrderedBag<T> and sub-ranges.
Write a program that finds a set of words (e.g. 1000 words) in a large text(e.g. 100 MB text file).
Print how many times each word occurs in the text.
Hint: you may find a C# trie in Internet.*/
var priorityQueue = new MyPriorityQueue<int>();
priorityQueue.Enqueue(1);
priorityQueue.Enqueue(3);
priorityQueue.Enqueue(18);
priorityQueue.Enqueue(4);
priorityQueue.Enqueue(105);
priorityQueue.Enqueue(213);
var last = priorityQueue.Dequeue();
Console.WriteLine("TASK 1:");
Console.WriteLine("Dequed: " + last);
Console.WriteLine("Size of queue: " + priorityQueue.Count());
Console.WriteLine("All elements: \n" + String.Join(", ", priorityQueue.All()));
Console.WriteLine();
/*Write a program to read a large collection of products (name + price) and efficiently find
the first 20 products in the price range [a…b].
Test for 500 000 products and 10 000 price searches.
Hint: you may use OrderedBag<T> and sub-ranges.*/
var db = new ProductsDb();
for (int i = 0; i < 500000; i++)
{
db.AddProduct(new Product(GetRandomName(), GetRandomPriceInRange(0, 100000)));
}
Console.WriteLine("TASK 2:");
Console.WriteLine("500 000 products added");
var stopWatch = new Stopwatch();
stopWatch.Start();
var productsInRange = db.GetProductsInPriceRange(100, 3000);
stopWatch.Stop();
Console.WriteLine("Alll products in this range: " + productsInRange.Count);
Console.WriteLine("Elapsed time to find all products: "+ stopWatch.Elapsed);
Console.WriteLine();
/*Write a program that finds a set of words(e.g. 1000 words) in a large text(e.g. 100 MB text file).
Print how many times each word occurs in the text.
Hint: you may find a C# trie in Internet.*/
var sw = new Stopwatch();
var trie = new Trie();
for (int i = 0; i < wordsToAdd; i++)
{
string word = GetRandomName();
sw.Start();
trie.Add(word);
sw.Stop();
}
Console.WriteLine("TASK 3");
Console.WriteLine("Added {0} words for {1} time", wordsToAdd, sw.Elapsed);
sw.Reset();
for (int i = 0; i < wordsToSearch; i++)
{
string word = GetRandomName();
sw.Start();
trie.GetWordOccurance(word);
sw.Stop();
}
Console.WriteLine("Found {0} words for {1} time", wordsToSearch, sw.Elapsed);
Console.WriteLine("Most common word: {0}", trie.GetMostCommonWord());
}