Palidrome Array
/*
* @(#)PalindromeArray.java 1.0 Apr 26, 2008
*
* The MIT License
*
* Copyright (c) 2008 Malachi de AElfweald <malachid@gmail.com>
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
//package org.eoti.math;
import java.math.BigInteger;
import java.util.Iterator;
import java.util.concurrent.ConcurrentHashMap;
public class PalidromeArray
implements Iterable<BigInteger>
{
protected static final BigInteger TWO = BigInteger.valueOf(2);
protected ConcurrentHashMap<BigInteger,BigInteger> array;
protected BigInteger totalLength, halfLength;
protected boolean isEven = true;
public static PalidromeArray fromString(String s)
{
String[] arr = s.split("\\|");
BigInteger[] bi = new BigInteger[arr.length];
for(int i=0; i<arr.length; i++)
bi[i] = new BigInteger(arr[i]);
return new PalidromeArray(bi);
}
public PalidromeArray(PalidromeArray array)
{
this.totalLength = array.totalLength;
this.halfLength = array.halfLength;
this.isEven = array.isEven;
this.array = new ConcurrentHashMap<BigInteger,BigInteger>();
for(BigInteger index : array.array.keySet())
this.array.put(index, array.array.get(index));
}
public PalidromeArray(BigInteger[] array)
{
this.totalLength = BigInteger.valueOf(array.length);
this.halfLength = totalLength.divide( TWO );
if( MathUtil.isOdd(totalLength))
{
isEven = false;
halfLength=halfLength.add(BigInteger.ONE);
}
this.array = new ConcurrentHashMap<BigInteger,BigInteger>();
BigInteger index = BigInteger.ZERO;
for(BigInteger bi : array)
{
this.array.put( index, bi );
index = index.add(BigInteger.ONE);
}
}
public PalidromeArray(BigInteger totalLength)
{
this.totalLength = totalLength;
this.halfLength = totalLength.divide( TWO );
if( MathUtil.isOdd(totalLength))
{
isEven = false;
halfLength=halfLength.add(BigInteger.ONE);
}
array = new ConcurrentHashMap<BigInteger,BigInteger>();
}
public String toString()
{
StringBuilder sb = new StringBuilder();
boolean first = true;
for(BigInteger bi : this)
{
if(!first) sb.append("|");
sb.append(bi);
first = false;
}
return sb.toString();
}
public BigInteger halfLength(){return halfLength;}
public BigInteger totalLength(){return totalLength;}
public BigInteger get(BigInteger position)
{
/**
* {1,4,6,4,1} would have {1,4,6} in our array
* 0: return 1
* 1: return 4
* 2: return 6
* 3: return 4
* 4: return 1
* totalLength = 5
* halfLength = 3
* get(0) returns #0
* get(1) returns #1
* get(2) returns #2
* get(3) returns #1
* get(4) returns #0
*
* {1,3,3,1} would have {1,3} in our array
* array.length = 2
* 0: return 1
* 1: return 3
* 2: return 3
* 3: return 1
* totalLength = 4
* halfLength = 2
* get(0) returns #0
* get(1) returns #1
* get(2) returns #1
* get(3) returns #0
*/
if(position.subtract(halfLength).signum() < 0)
return array.get(position);
BigInteger mid = halfLength.subtract(BigInteger.ONE);
if(isEven)
return array.get( mid.subtract( position.subtract(halfLength) ));
return array.get( mid.subtract( position.subtract(mid) ));
}
public void set(BigInteger position, BigInteger value){array.put(position, value);}
public Iterator<BigInteger> iterator()
{
return new PalidromeArrayIterator(this);
}
class PalidromeArrayIterator
implements Iterator<BigInteger>
{
protected PalidromeArray array;
protected BigInteger position = BigInteger.ZERO;
public PalidromeArrayIterator(PalidromeArray array)
{
this.array = array;
}
public boolean hasNext()
{
return array.totalLength.subtract(position).signum() > 0;
}
public BigInteger next()
{
BigInteger index = position;
position = position.add(BigInteger.ONE);
return array.get(index);
}
public void remove()
{
throw new UnsupportedOperationException("Not supported");
}
}
}
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