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Gemini is a web framework created by TechEmpower.
/*******************************************************************************
* Copyright (c) 2018, TechEmpower, Inc.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* * Neither the name TechEmpower, Inc. nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL TECHEMPOWER, INC. BE LIABLE FOR ANY DIRECT,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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*******************************************************************************/
package com.techempower.collection;
import java.util.*;
/**
* This class provides the ability to compare two sets of ints, provided
* as int arrays, and resulting in two differences arrays and a superset
* array.
*/
public class IntegerSetComparison
{
//
// Member variables.
//
private int[] setA, setB, aSorted, bSorted, aMinusB, bMinusA, superSet;
private int largerSize;
private int smallerSize;
private boolean computed = false;
//
// Member methods.
//
/**
* Constructor.
*/
public IntegerSetComparison(int[] setA, int[] setB)
{
this.setA = setA;
this.setB = setB;
// Determine the larger and smaller size. These sizes are used to
// create temporary arrays to capture the differences (can't be any
// larger than the larger array) and the superset (can't be any larger
// than the two arrays together).
if (setA.length > setB.length)
{
this.largerSize = setA.length;
this.smallerSize = setB.length;
}
else
{
this.largerSize = setB.length;
this.smallerSize = setA.length;
}
}
/**
* Computes the resulting arrays if they have not yet been computed.
*/
public void computeIfNeeded()
{
if (!this.computed)
{
compute();
}
}
/**
* Computes the resulting arrays.
*/
public void compute()
{
// Create sorted versions of the original sets.
this.aSorted = new int[this.setA.length];
this.bSorted = new int[this.setB.length];
System.arraycopy(this.setA, 0, this.aSorted, 0, this.setA.length);
System.arraycopy(this.setB, 0, this.bSorted, 0, this.setB.length);
// The sort operation is usually, by a large margin, the most time-
// consuming operation.
Arrays.sort(this.aSorted);
Arrays.sort(this.bSorted);
// Create temporary comparison arrays.
int[] tempAminusB = new int[this.largerSize];
int[] tempBminusA = new int[this.largerSize];
int[] tempSuper = new int[this.largerSize + this.smallerSize];
int positionA = 0, positionB = 0, nextA = 0, nextB = 0;
int positionAminusB = 0, positionBminusA = 0, positionSuper = 0;
// Compare the two sorted arrays and create the differences and superset
// arrays.
while ( (positionA < this.aSorted.length)
|| (positionB < this.bSorted.length)
)
{
if (positionA < this.aSorted.length)
{
nextA = this.aSorted[positionA];
}
else
{
nextA = Integer.MAX_VALUE;
}
if (positionB < this.bSorted.length)
{
nextB = this.bSorted[positionB];
}
else
{
nextB = Integer.MAX_VALUE;
}
// The next item is unique to set A.
if (nextA < nextB)
{
tempAminusB[positionAminusB++] = nextA;
tempSuper[positionSuper++] = nextA;
positionA++;
}
// The next item is unique to set B.
else if (nextB < nextA)
{
tempBminusA[positionBminusA++] = nextB;
tempSuper[positionSuper++] = nextB;
positionB++;
}
// The next item is in both sets.
else
{
tempSuper[positionSuper++] = nextA;
positionA++;
positionB++;
}
}
// Shrink the temporary arrays and copy them over to the main arrays.
this.aMinusB = new int[positionAminusB];
this.bMinusA = new int[positionBminusA];
this.superSet = new int[positionSuper];
System.arraycopy(tempAminusB, 0, this.aMinusB, 0, positionAminusB);
System.arraycopy(tempBminusA, 0, this.bMinusA, 0, positionBminusA);
System.arraycopy(tempSuper, 0, this.superSet, 0, positionSuper);
// Set the computed flag.
this.computed = true;
}
/**
* Gets the original Set A.
*/
public int[] getSetA()
{
return this.setA;
}
/**
* Gets the original Set B.
*/
public int[] getSetB()
{
return this.setB;
}
/**
* Gets Set A sorted in ascending order.
*/
public int[] getSetASorted()
{
computeIfNeeded();
return this.aSorted;
}
/**
* Gets Set B sorted in ascending order.
*/
public int[] getSetBSorted()
{
computeIfNeeded();
return this.bSorted;
}
/**
* Gets the differences set of A minus B (A-B).
*/
public int[] getAMinusB()
{
computeIfNeeded();
return this.aMinusB;
}
/**
* Gets the differences set of B minus A (B-A).
*/
public int[] getBMinusA()
{
computeIfNeeded();
return this.bMinusA;
}
/**
* Gets the super set of A+B. Only one instance of each ID will be
* included; duplicates are removed.
*/
public int[] getSuperset()
{
computeIfNeeded();
return this.superSet;
}
} // End IntegerSetComparison.