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/*
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Copyright (c) 2003-2006 Niels Kokholm and Peter Sestoft
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Permission is hereby granted, free of charge, to any person obtaining a copy
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of this software and associated documentation files (the "Software"), to deal
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in the Software without restriction, including without limitation the rights
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to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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copies of the Software, and to permit persons to whom the Software is
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furnished to do so, subject to the following conditions:
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The above copyright notice and this permission notice shall be included in
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all copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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SOFTWARE.
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*/
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// C5 example: functional sets 2004-12-21
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// Compile with
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// csc /r:C5.dll Sets.cs
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using System;
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using System.Text;
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using C5;
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using SCG = System.Collections.Generic;
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namespace Sets {
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// The class of sets with item type T, implemented as a subclass of
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// HashSet<T> but with functional infix operators * + - that compute
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// intersection, union and difference functionally. That is, they
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// create a new set object instead of modifying an existing one.
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// The hasher is automatically created so that it is appropriate for
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// T. In particular, this is true when T has the form Set<W> for
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// some W, since Set<W> implements ICollectionValue<W>.
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public class Set<T> : HashSet<T> {
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public Set(SCG.IEnumerable<T> enm) : base() {
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AddAll(enm);
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}
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public Set(params T[] elems) : this((SCG.IEnumerable<T>)elems) { }
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// Set union (+), difference (-), and intersection (*):
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public static Set<T> operator +(Set<T> s1, Set<T> s2) {
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if (s1 == null || s2 == null)
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throw new ArgumentNullException("Set+Set");
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else {
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Set<T> res = new Set<T>(s1);
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res.AddAll(s2);
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return res;
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}
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}
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public static Set<T> operator -(Set<T> s1, Set<T> s2) {
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if (s1 == null || s2 == null)
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throw new ArgumentNullException("Set-Set");
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else {
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Set<T> res = new Set<T>(s1);
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res.RemoveAll(s2);
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return res;
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}
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}
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public static Set<T> operator *(Set<T> s1, Set<T> s2) {
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if (s1 == null || s2 == null)
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throw new ArgumentNullException("Set*Set");
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else {
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Set<T> res = new Set<T>(s1);
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res.RetainAll(s2);
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return res;
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}
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}
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// Equality of sets; take care to avoid infinite loops
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public static bool operator ==(Set<T> s1, Set<T> s2) {
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return EqualityComparer<Set<T>>.Default.Equals(s1, s2);
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}
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public static bool operator !=(Set<T> s1, Set<T> s2) {
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return !(s1 == s2);
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}
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public override bool Equals(Object that) {
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return this == (that as Set<T>);
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}
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public override int GetHashCode() {
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return EqualityComparer<Set<T>>.Default.GetHashCode(this);
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}
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// Subset (<=) and superset (>=) relation:
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public static bool operator <=(Set<T> s1, Set<T> s2) {
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if (s1 == null || s2 == null)
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throw new ArgumentNullException("Set<=Set");
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else
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return s1.ContainsAll(s2);
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}
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public static bool operator >=(Set<T> s1, Set<T> s2) {
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if (s1 == null || s2 == null)
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throw new ArgumentNullException("Set>=Set");
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else
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return s2.ContainsAll(s1);
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}
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public override String ToString() {
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StringBuilder sb = new StringBuilder();
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sb.Append("{");
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bool first = true;
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foreach (T x in this) {
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if (!first)
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sb.Append(",");
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sb.Append(x);
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first = false;
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}
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sb.Append("}");
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return sb.ToString();
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}
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}
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class MyTest {
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public static void Main(String[] args) {
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Set<int> s1 = new Set<int>(2, 3, 5, 7, 11);
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Set<int> s2 = new Set<int>(2, 4, 6, 8, 10);
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Console.WriteLine("s1 + s2 = {0}", s1 + s2);
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Console.WriteLine("s1 * s2 = {0}", s1 * s2);
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Console.WriteLine("s1 - s2 = {0}", s1 - s2);
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Console.WriteLine("s1 - s1 = {0}", s1 - s1);
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Console.WriteLine("s1 + s1 == s1 is {0}", s1 + s1 == s1);
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Console.WriteLine("s1 * s1 == s1 is {0}", s1 * s1 == s1);
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Set<Set<int>> ss1 = new Set<Set<int>>(s1, s2, s1 + s2);
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Console.WriteLine("ss1 = {0}", ss1);
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Console.WriteLine("IntersectionClose(ss1) = {0}", IntersectionClose(ss1));
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Set<Set<int>> ss2 =
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new Set<Set<int>>(new Set<int>(2, 3), new Set<int>(1, 3), new Set<int>(1, 2));
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Console.WriteLine("ss2 = {0}", ss2);
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Console.WriteLine("IntersectionClose(ss2) = {0}", IntersectionClose(ss2));
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}
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// Given a set SS of sets of Integers, compute its intersection
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// closure, that is, the least set TT such that SS is a subset of TT
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// and such that for any two sets t1 and t2 in TT, their
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// intersection is also in TT.
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// For instance, if SS is {{2,3}, {1,3}, {1,2}},
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// then TT is {{2,3}, {1,3}, {1,2}, {3}, {2}, {1}, {}}.
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// Both the argument and the result is a Set<Set<int>>
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static Set<Set<T>> IntersectionClose<T>(Set<Set<T>> ss) {
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IQueue<Set<T>> worklist = new CircularQueue<Set<T>>();
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foreach (Set<T> s in ss)
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worklist.Enqueue(s);
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HashSet<Set<T>> tt = new HashSet<Set<T>>();
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while (worklist.Count != 0) {
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Set<T> s = worklist.Dequeue();
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foreach (Set<T> t in tt) {
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Set<T> ts = t * s;
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if (!tt.Contains(ts))
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worklist.Enqueue(ts);
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}
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tt.Add(s);
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}
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return new Set<Set<T>>((SCG.IEnumerable<Set<T>>)tt);
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}
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}
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}
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