使用有偏的无偏随机数生成器 [英] Unbiased random number generator using a biased one
问题描述
您有一个偏向随机数生成器,该生成器生成概率为p的1和概率为(1-p)的0。您不知道p的值。使用此函数生成一个无偏随机数生成器,该生成器生成概率为0.5的1和概率为0.5的0。
You have a biased random number generator that produces a 1 with a probability p and 0 with a probability (1-p). You do not know the value of p. Using this make an unbiased random number generator which produces 1 with a probability 0.5 and 0 with a probability 0.5.
注意:此问题是练习题来自Cormen,Leiserson,Rivest,Stein的《算法介绍》。(clrs)
Note: this problem is an exercise problem from Introduction to Algorithms by Cormen, Leiserson, Rivest, Stein.(clrs)
推荐答案
事件(p)(1 -p)和(1-p)(p)是等概率的。
The events (p)(1-p) and (1-p)(p) are equiprobable. Taking them as 0 and 1 respectively and discarding the other two pairs of results you get an unbiased random generator.
在代码中,将它们分别设为0和1并丢弃其他两对结果,将得到一个无偏的随机生成器。
In code this is done as easy as:
int UnbiasedRandom()
{
int x, y;
do
{
x = BiasedRandom();
y = BiasedRandom();
} while (x == y);
return x;
}
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