randomized-algorithm/random

/**
 * Builds a randint function given a random number generator.
 *
 * @param {Function} random A function taking no arguments that returns a
 * double uniformly at random in the interval [0, 1).
 *
 * @return {Function} A randint function.
 */
const _randint = (random) => {
    /**
     * Returns an integer in interval [i, j[ (i included, j excluded)
     * according to a uniform distribution.
     *
     * @param {number} i The inclusive left bound
     * @param {number} j The non-inclusive right bound
     * @return {number} An integer in the interval [i, j[ taken uniformly at
     * random.
     */
    const randint = (i, j) => i + Math.floor(random() * (j - i));
    return randint;
};

export default _randint;