給一個函數，返回 0 和 1，概率爲 p 和 1-p，請你實現一個函數，使得返回 01 概率一樣

1、給一個函數，返回 0 和 1，概率爲 p 和 1-p，請你實現一個函數，使得返回 01 概率一樣。

答案：

import java.util.Random;

public class RandomTest {

    /**
     * assume:
     * Rate(zero) = p
     * Rate(one) = 1 - p
     */
    public static int generateZeroAndOne() {
        return new Random().nextInt(2);
    }

    /**
     * so:
     * Rate(zero) = 1 - p
     * Rate(one) = p
     */
    public static int generateOneAndZero() {
        return 1 - generateZeroAndOne();
    }

    /**
     * though looks (Rate(zero) = p * (1 - p)) == (Rate(one) = (1 - p) * p)
     * but:
     * 1 * 1 -> 1
     * 1 * 0 -> 0
     * 0 * 1 -> 0
     * 0 * 0 -> 0
     * Rate(zero) = 3 / 4 * p * (1 - p)
     * Rate(one) = 1 / 4 * (1 - p) * p
     * <p>
     * <p>
     * 1 == 1 -> true
     * 1 == 0 -> false
     * 0 == 1 -> false
     * 0 == 0 -> true
     * Rate(zero) = 1 / 2 * p * (1 - p)
     * Rate(one) = 1 / 2 * (1 - p) * p
     */
    public static int rate() {
        int a = generateOneAndZero();//zero: 1-p  one: p
        int b = generateZeroAndOne();//zero: p    one: 1-p
        //1 means (a = 1 and b = 0)  or (a is 0 and b = 1)
        //0 means (a = 0 and b = 0) or (a == 1 and b == 1)
        return a ^ b;

    }

}

答案爲原創。