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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(final int value, final 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 winning
* The number of winning possibilities.
*
* @param total
* 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(final int winning, final int total,
final Function<Integer, Integer> rng) {
return rng.apply(total) < winning;
}
/**
* Check if a number is in an inclusive range.
*
* @param min
* The minimum value of the range.
*
* @param max
* The maximum value of the range.
*
* @param i
* The number to check.
*
* @return Whether the number is in the range.
*/
public static boolean between(final int min, final int max, final int i) {
return i >= min && i <= max;
}
}
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