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#14386. 百奇

الإحصائيات

让我们来谈谈吃百奇(Pocky)棒的事。这里有一根涂层上带有彩色装饰条纹的 Decorer 百奇棒,长度为 $L$。

当剩余百奇棒的长度大于 $d$ 时,我们执行以下步骤:我们在剩余的百奇棒上的任意位置等概率地将其折断,这会将剩余的百奇棒分成两部分。取左边的一部分并吃掉。当剩余长度不大于 $d$ 时,我们不再重复此步骤。

现在我们想知道我们需要重复上述步骤的期望次数。结果四舍五入保留到小数点后 6 位。

输入格式

输入的第一行包含一个整数 $N$,表示测试用例的数量。

接下来的 $N$ 行,每行包含两个浮点数 $L$ 和 $d$,最多保留小数点后 5 位,满足 $1 \le d, L \le 150$。

输出格式

对于每个测试用例,在一行中输出期望的重复次数,四舍五入保留到小数点后 6 位。

样例

样例输入 1

6
1.0 1.0
2.0 1.0
4.0 1.0
8.0 1.0
16.0 1.0
7.00 3.00

样例输出 1

0.000000
1.693147
2.386294
3.079442
3.772589
1.847298

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