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AIMA-Java Core Algorithms from the book Artificial Intelligence a Modern Approach 3rd Ed.
package aima.core.util.math;
import java.util.List;
/**
* For details on Mixed Radix Number Representations.
*
* @author Ciaran O'Reilly
* @author Mike Stampone
*/
public class MixedRadixNumber extends Number {
//
private static final long serialVersionUID = 1L;
//
private long value = 0L;
private long maxValue = 0L;
private int[] radices = null;
private int[] currentNumeralValue = null;
private boolean recalculate = true;
/**
* Constructs a mixed radix number with a specified value and a specified
* array of radices.
*
* @param value
* the value of the mixed radix number
* @param radices
* the radices used to represent the value of the mixed radix
* number
*/
public MixedRadixNumber(long value, int[] radices) {
this.value = value;
this.radices = new int[radices.length];
System.arraycopy(radices, 0, this.radices, 0, radices.length);
calculateMaxValue();
}
/**
* Constructs a mixed radix number with a specified value and a specified
* list of radices.
*
* @param value
* the value of the mixed radix number
* @param radices
* the radices used to represent the value of the mixed radix
* number
*/
public MixedRadixNumber(long value, List radices) {
this.value = value;
this.radices = new int[radices.size()];
for (int i = 0; i < radices.size(); i++) {
this.radices[i] = radices.get(i);
}
calculateMaxValue();
}
/**
* Constructs a mixed radix number with a specified array of numerals and a
* specified array of radices.
*
* @param radixValues
* the numerals of the mixed radix number
* @param radices
* the radices of the mixed radix number
*/
public MixedRadixNumber(int[] radixValues, int[] radices) {
this(0, radices);
setCurrentValueFor(radixValues);
}
/**
* Returns the value of the mixed radix number with the specified array of
* numerals and the current array of radices.
*
* @return the value of the mixed radix number
*
* @throws IllegalArgumentException
* if any of the specified numerals is less than zero, or if any
* of the specified numerals is greater than it's corresponding
* radix.
*/
public long getCurrentValueFor(int[] radixValues) {
if (radixValues.length != radices.length) {
throw new IllegalArgumentException(
"Radix values not same size as Radices.");
}
long cvalue = 0;
long mvalue = 1;
for (int i = 0; i < radixValues.length; i++) {
if (radixValues[i] < 0 || radixValues[i] >= radices[i]) {
throw new IllegalArgumentException("Radix value " + i
+ " is out of range for radix at this position");
}
if (i > 0) {
mvalue *= radices[i - 1];
}
cvalue += mvalue * radixValues[i];
}
return cvalue;
}
/**
* Sets the value of the mixed radix number with the specified array of
* numerals and the current array of radices.
*
* @param radixValues
* the numerals of the mixed radix number
*/
public void setCurrentValueFor(int[] radixValues) {
this.value = getCurrentValueFor(radixValues);
System.arraycopy(radixValues, 0, this.currentNumeralValue, 0,
radixValues.length);
recalculate = false;
}
/**
* Returns the maximum value which can be represented by the current array
* of radices.
*
* @return the maximum value which can be represented by the current array
* of radices.
*/
public long getMaxAllowedValue() {
return maxValue;
}
/**
* Increments the value of the mixed radix number, if the value is less than
* the maximum value which can be represented by the current array of
* radices.
*
* @return true if the increment was successful.
*/
public boolean increment() {
if (value < maxValue) {
value++;
recalculate = true;
return true;
}
return false;
}
/**
* Decrements the value of the mixed radix number, if the value is greater
* than zero.
*
* @return true if the decrement was successful.
*/
public boolean decrement() {
if (value > 0) {
value--;
recalculate = true;
return true;
}
return false;
}
/**
* Returns the numeral at the specified position.
*
* @param atPosition
* the position of the numeral to return
* @return the numeral at the specified position.
*/
public int getCurrentNumeralValue(int atPosition) {
if (atPosition >= 0 && atPosition < radices.length) {
if (recalculate) {
long quotient = value;
for (int i = 0; i < radices.length; i++) {
if (0 != quotient) {
currentNumeralValue[i] = (int) quotient % radices[i];
quotient = quotient / radices[i];
} else {
currentNumeralValue[i] = 0;
}
}
recalculate = false;
}
return currentNumeralValue[atPosition];
}
throw new IllegalArgumentException(
"Argument atPosition must be >=0 and < " + radices.length);
}
//
// START-Number
@Override
public int intValue() {
return (int) longValue();
}
@Override
public long longValue() {
return value;
}
@Override
public float floatValue() {
return longValue();
}
@Override
public double doubleValue() {
return longValue();
}
// END-Number
//
@Override
public String toString() {
StringBuilder sb = new StringBuilder();
for (int i = 0; i < radices.length; i++) {
sb.append("[");
sb.append(this.getCurrentNumeralValue(i));
sb.append("]");
}
return sb.toString();
}
//
// PRIVATE
//
/**
* Sets the maximum value which can be represented by the current array of
* radices.
*
* @throws IllegalArgumentException
* if no radices are defined, if any radix is less than two, or
* if the current value is greater than the maximum value which
* can be represented by the current array of radices.
*/
private void calculateMaxValue() {
if (0 == radices.length) {
throw new IllegalArgumentException(
"At least 1 radix must be defined.");
}
for (int i = 0; i < radices.length; i++) {
if (radices[i] < 2) {
throw new IllegalArgumentException(
"Invalid radix, must be >= 2");
}
}
// Calculate the maxValue allowed
maxValue = radices[0];
for (int i = 1; i < radices.length; i++) {
maxValue *= radices[i];
}
maxValue -= 1;
if (value > maxValue) {
throw new IllegalArgumentException(
"The value ["
+ value
+ "] cannot be represented with the radices provided, max value is "
+ maxValue);
}
currentNumeralValue = new int[radices.length];
}
}