/// <summary>
/// Dijkstra algorithm (longest path) based on graph g for start vertice s. Positive cycles are NOT allowed in longest path algorithm
/// </summary>
/// <param name="g">Graph for search</param>
/// <param name="s">Start vertice</param>
public static PathStats LongestPath(GraphBase g, int s)
{
var ps = new PathStats(g.V);
for (var i = 0; i < ps.Dist.Length; i++)
{
ps.Dist[i] = int.MinValue;
ps.Prev[i] = -1;
}
ps.Dist[s] = 0;//start vertice
var pq = new IndexMaxPQ<Distance>(ps.Dist.Length);
for (int i = 0; i < ps.Dist.Length; i++)
{
pq.Insert(i, new Distance { V = i, Dist = ps.Dist[i] });
}
while (!pq.IsEmpty())
{
var v = pq.DelRoot();
foreach (var e in g.Adjacent(v))
{
if (ps.Dist[e.V2] < ps.Dist[v] + e.Weight) //longest path
{
ps.Dist[e.V2] = ps.Dist[v] + e.Weight;
ps.Prev[e.V2] = v;
pq.ChangeKey(e.V2, new Distance { V = e.V2, Dist = ps.Dist[e.V2] });
}
}
}
return ps;
}
public void Initialize()
{
_target = new IndexMaxPQ<Distance>(4);
_target.Insert(2, new Distance { V = 2, Dist = 1 });
_target.Insert(1, new Distance { V = 1, Dist = 3 });
_target.Insert(0, new Distance { V = 0, Dist = 2 });
}
public void EnumeratorMaxPQTest()
{
// Expected: same as sorting the input and inserting it in a regular queue
Queue<string> expectedItems = new Queue<string>(this.testStrings.OrderByDescending(s => s));
IndexMaxPQ<string> pq = new IndexMaxPQ<string>(this.testStrings.Length);
CommonIndexPQUnitTests.EnumerationPQTest(this.testStrings, pq, expectedItems);
}
public void IndexedMaxPQIncreaseKeyTest()
{
// arrange
var pq = new IndexMaxPQ <string>(array);
// act + assert initial
Assert.False(pq.IsEmpty);
Assert.Equal(10, pq.Size);
Assert.Equal(9, pq.Index);
Assert.Equal(9, pq.MaxIndex);
Assert.Equal("worst", pq.Max);
Assert.Equal("worst", pq.TopKey);
// act + assert ex
try
{
pq.increaseKey(9, "exception");
}
catch (Exception ex)
{
Assert.IsType <ArgumentException>(ex);
Assert.Equal("Calling increaseKey() with given argument would not strictly increase the key", ex.Message);
}
// act + assert increase
pq.increaseKey(9, "worst even");
Assert.Equal("worst even", pq.Max);
Assert.Equal("worst even", pq.TopKey);
}
public void IndexMaxPQIteratorTest()
{
var pq = new IndexMaxPQ <String>(array);
var actual = Strings(pq).ToList();
Assert.Equal(indexedMax, actual);
}
public void Merge3WayMaxPQTest()
{
string[] inputFiles = { "Algs4-Data\\m1r.txt", "Algs4-Data\\m2r.txt", "Algs4-Data\\m3r.txt" };
Queue<string> expectedItems = new Queue<string>(
"A B C F G I I Z B D H P Q Q A B E F J N".Split(" ".ToCharArray()).OrderByDescending(s => s));
IndexMaxPQ<string> pq = new IndexMaxPQ<string>(expectedItems.Count);
CommonIndexPQUnitTests.MergeMultiWay(inputFiles, pq, expectedItems);
}
public void Run()
{
Console.WriteLine("Choose file:"); // Prompt
Console.WriteLine("1 - tinyPQ.txt"); // Prompt
Console.WriteLine("or quit"); // Prompt
var fileNumber = Console.ReadLine();
var fieName = string.Empty;
switch (fileNumber)
{
case "1":
fieName = "tinyIndexPQ.txt";
break;
case "quit":
return;
default:
return;
}
var @in = new In($"Files\\Sorting\\{fieName}");
var words = @in.ReadAllStrings();
//var list = words.Select(word => new StringComparable(word)).ToList();
//var listComparable = list.Cast<IComparable>().ToList();
//var arrayComparable = list.Cast<IComparable>().ToArray();
var listStrings = words.ToList();
var pq = new IndexMaxPQ <string>(listStrings.Count);
//Fill Priority Queue
for (var i = 0; i < listStrings.Count; i++)
{
pq.Insert(i, listStrings[i]);
}
// print results
foreach (var item in pq)
{
Console.WriteLine(pq.KeyOf(item));
}
Console.ReadLine();
}
public void IndexMaxPQTest1()
{
const int MaxSize = 8;
const double MinValue = 3.9;
const double MaxValue = MinValue * MaxSize + 32;
int index;
// MaxValue index == 3, MinValue index == 4
double[] items = { MinValue * 2, MinValue * 3, MinValue * 4, MaxValue, MinValue, MinValue * 5, MinValue * 6, MinValue * 7 };
StdRandom.Seed = 101;
IndexMaxPQ <double> pq = new IndexMaxPQ <double>(MaxSize);
index = StdRandom.Uniform(items.Length);
Assert.IsFalse(pq.Contains(index));
Assert.IsTrue(pq.IsEmpty);
Assert.AreEqual(0, pq.Count);
try
{
index = pq.DelMax();
Assert.Fail("Failed to catch exception");
}
catch (InvalidOperationException) { }
for (int i = 0; i < items.Length; i++)
{
pq.Insert(i, items[i]);
}
Assert.AreEqual(items.Length, pq.Count);
Assert.AreEqual(MaxValue, pq.MaxKey);
Assert.AreEqual(3, pq.MaxIndex);
Assert.AreEqual(MinValue, pq.KeyOf(4));
index = StdRandom.Uniform(items.Length);
Assert.AreEqual(items[index], pq.KeyOf(index));
pq.ChangeKey(1, pq.MaxKey * 1.9); // make it the largest item
Assert.AreEqual(1, pq.MaxIndex);
pq.IncreaseKey(3, pq.MaxKey * 1.87);
Assert.AreEqual(3, pq.MaxIndex);
pq.Delete(3);
Assert.AreNotEqual(3, pq.MaxIndex);
Assert.AreEqual(1, pq.DelMax());
}
public void IndexPQDeleteAtIndexTest()
{
var pq = new IndexMaxPQ <String>(array);
Assert.True(pq.Contains(5));
pq.Delete(5);
Assert.False(pq.Contains(5));
try
{
pq.Delete(5);
}
catch (Exception ex)
{
Assert.IsType <InvalidOperationException>(ex);
Assert.Equal("index is not in the priority queue", ex.Message);
}
}
public void Run()
{
Console.WriteLine("Choose file:"); // Prompt
Console.WriteLine("1 - tinyPQ.txt"); // Prompt
Console.WriteLine("or quit"); // Prompt
var fileNumber = Console.ReadLine();
var fieName = string.Empty;
switch (fileNumber)
{
case "1":
fieName = "tinyIndexPQ.txt";
break;
case "quit":
return;
default:
return;
}
var @in = new In($"Files\\Sorting\\{fieName}");
var words = @in.ReadAllStrings();
//var list = words.Select(word => new StringComparable(word)).ToList();
//var listComparable = list.Cast<IComparable>().ToList();
//var arrayComparable = list.Cast<IComparable>().ToArray();
var listStrings = words.ToList();
var pq = new IndexMaxPQ<string>(listStrings.Count);
//Fill Priority Queue
for (var i = 0; i < listStrings.Count; i++)
{
pq.Insert(i, listStrings[i]);
}
// print results
foreach (var item in pq)
{
Console.WriteLine(pq.KeyOf(item));
}
Console.ReadLine();
}
/**
* Returns the cut-of-the-phase. The cut-of-the-phase is a minimum s-t-cut
* in the current graph, where {@code s} and {@code t} are the two vertices
* added last in the phase. This algorithm is known in the literature as
* <em>maximum adjacency search</em> or <em>maximum cardinality search</em>.
*
* @param G the edge-weighted graph
* @param marked the array of contracted vertices, where {@code marked[v]}
* is {@code true} if the vertex {@code v} was already
* contracted; or {@code false} otherwise
* @param cp the previous cut-of-the-phase
* @return the cut-of-the-phase
*/
private CutPhase minCutPhase(EdgeWeightedGraph G, boolean[] marked, CutPhase cp) {
IndexMaxPQ<Double> pq = new IndexMaxPQ<Double>(G.V());
for (int v = 0; v < G.V(); v++) {
if (v != cp.s && !marked[v]) pq.insert(v, 0.0);
}
pq.insert(cp.s, Double.POSITIVE_INFINITY);
while (!pq.isEmpty()) {
int v = pq.delMax();
cp.s = cp.t;
cp.t = v;
for (Edge e : G.adj(v)) {
int w = e.other(v);
if (pq.contains(w)) pq.increaseKey(w, pq.keyOf(w) + e.weight());
}
}
cp.weight = 0.0;
for (Edge e : G.adj(cp.t)) {
cp.weight += e.weight();
}
return cp;
}
// 书中算法 2.6 给出的是最大堆，但本题自带的部分解答是最小堆形式的。
// 这里和官网保持一致，实现最大堆。
// 官网答案：https://algs4.cs.princeton.edu/24pq/IndexMaxPQ.java.html
static void Main(string[] args)
{
string[] input = new string[] { "it", "was", "the", "best", "of", "times", "it", "was", "the", "worst" };
IndexMaxPQ <string> pq = new IndexMaxPQ <string>(input.Length);
for (int i = 0; i < input.Length; i++)
{
pq.Insert(input[i], i);
}
foreach (var i in pq)
{
Console.WriteLine(i + ". " + input[i]);
}
Console.WriteLine();
Random random = new Random();
for (int i = 0; i < input.Length; i++)
{
if (random.NextDouble() < 0.5)
{
pq.IncreaseKey(i, input[i] + input[i]);
}
else
{
pq.DecreaseKey(i, input[i].Substring(0, 1));
}
}
while (!pq.IsEmpty())
{
string key = pq.MaxKey();
int i = pq.DelMax();
Console.WriteLine(i + "." + key);
}
Console.WriteLine();
for (int i = 0; i < input.Length; i++)
{
pq.Insert(input[i], i);
}
int[] param = new int[input.Length];
for (int i = 0; i < input.Length; i++)
{
param[i] = i;
}
Shuffle(param);
for (int i = 0; i < param.Length; i++)
{
string key = pq.KeyOf(param[i]);
pq.Delete(param[i]);
Console.WriteLine(param[i] + "." + key);
}
}
// Use this for initialization
void Start()
{
// insert a bunch of strings
string[] strings = { "it", "was", "the", "best", "of", "times", "it", "was", "the", "worst" };
IndexMaxPQ <string> pq = new IndexMaxPQ <string>(strings.Length);
for (int i = 0; i < strings.Length; i++)
{
pq.insert(i, strings[i]);
}
// print each key using the iterator
foreach (string i in pq)
{
print(i + " " + strings[int.Parse(i)]);
}
// increase or decrease the key
for (int i = 0; i < strings.Length; i++)
{
if (Random.Range(0.0f, 1.0f) < 0.5) // Random.uniform() 返回一个随机的范围在[0,1)之间的double类型的数
{
pq.increaseKey(i, strings[i] + strings[i]);
}
else
{
pq.decreaseKey(i, strings[i].Substring(0, 1));
}
}
// delete and print each key
while (!pq.isEmpty())
{
string key = pq.maxKey();
int i = pq.delMax();
print(i + " " + key);
}
// reinsert the same strings
for (int i = 0; i < strings.Length; i++)
{
pq.insert(i, strings[i]);
}
// delete them in random order
int[] perm = new int[strings.Length];
for (int i = 0; i < strings.Length; i++)
{
perm[i] = i;
}
UnSort(perm); // StdRandom.shuffle() 随机打乱指定的object型数组
for (int i = 0; i < perm.Length; i++)
{
string key = pq.keyOf(perm[i]);
pq.delete(perm[i]);
print(perm[i] + " " + key);
}
}
