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package bjc.utils.funcutils;
import java.util.function.Function;
/**
* Utility functions for dealing with numbers
*
* @author ben
*
*/
public class NumberUtils {
/**
* Compute the falling factorial of a number
*
* @param value
* The number to compute
* @param power
* The power to do the falling factorial for
* @return The falling factorial of the number to the power
*/
public static int fallingFactorial(int value, int power) {
if (power == 0) {
return 1;
} else if (power == 1) {
return value;
} else {
int result = 1;
for (int currentSub = 0; currentSub < power + 1;
currentSub++) {
result *= value - currentSub;
}
return result;
}
}
/**
* Evaluates a linear probability distribution
*
* @param topExp
* The number of winning possibilities
* @param bottomExp
* The number of total possibilities
* @param rng
* The function to use to generate a random possibility
* @return Whether or not a random possibility was a winning one
*/
public static boolean isProbable(int topExp, int bottomExp,
Function<Integer, Integer> rng) {
return rng.apply(bottomExp) < topExp;
}
}
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