Android Open Source - dice-probabilities Forced Reroll Special

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License

The source code is released under:

MIT License

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Java Source Code

package org.kleemann.diceprobabilities.special;
//  w  w  w.ja v a 2 s.co m
import org.apache.commons.math3.fraction.BigFraction;
import org.kleemann.diceprobabilities.R;
import org.kleemann.diceprobabilities.distribution.Distribution;
import org.kleemann.diceprobabilities.distribution.ScaleCumulativeDistribution;

import android.content.res.Resources;
import android.util.SparseIntArray;

/**
 * <p>
 * If the first roll succeeds, you must successfully roll again in order to
 * succeed.
 */
class ForcedRerollSpecial extends AbstractSpecial {

  public ForcedRerollSpecial(Resources r) {
    super(r.getString(R.string.special_forced_reroll_title), r
        .getString(R.string.special_forced_reroll_description));
  }

  @Override
  public Distribution getDistribution(SparseIntArray sidesToCount) {
    Distribution d = super.getDistribution(sidesToCount);

    return ScaleCumulativeDistribution.scale(d,
        new ScaleCumulativeDistribution.Scale() {
          public BigFraction scale(BigFraction pS, int x) {
            // P(S) = 1 - P(F)
            // P(new) = 1 - ( P(F) + P(S) * P(F) )
            final BigFraction pF = BigFraction.ONE.subtract(pS);
            return BigFraction.ONE.subtract(pF.add(pS.multiply(pF)));
          }
        });
  }
}

Java Source Code List