After defeating a Blacklist Rival, you get a chance to draw $1$ reward slip out of $x$ hidden valid slips. Initially, $x=3$ and these hidden valid slips are Cash Slip, Impound Strike Release Marker and Pink Slip of Rival's Car. Initially, the probability of drawing these in a random guess are $c$, $m$, and $p$, respectively. There is also a volatility factor $v$. You can play any number of Rival Races as long as you don't draw a Pink Slip. Assume that you win each race and get a chance to draw a reward slip. In each draw, you draw one of the $x$ valid items with their respective probabilities. Suppose you draw a particular item and its probability of drawing before the draw was $a$. Then,
- If the item was a Pink Slip, the quest is over, and you will not play any more races.
- Otherwise,
- If
$a\leq v$, the probability of the item drawn becomes$0$and the item is no longer a valid item for all the further draws, reducing$x$by$1$. Moreover, the reduced probability$a$is distributed equally among the other remaining valid items.- If
$a \gt v$, the probability of the item drawn reduces by$v$and the reduced probability is distributed equally among the other valid items.
- If
For example,
- If
$(c,m,p)=(0.2,0.1,0.7)$and$v=0.1$, after drawing Cash, the new probabilities will be$(0.1,0.15,0.75)$. - If
$(c,m,p)=(0.1,0.2,0.7)$and$v=0.2$, after drawing Cash, the new probabilities will be$(Invalid,0.25,0.75)$. - If
$(c,m,p)=(0.2,Invalid,0.8)$and$v=0.1$, after drawing Cash, the new probabilities will be$(0.1,Invalid,0.9)$. - If
$(c,m,p)=(0.1,Invalid,0.9)$and$v=0.2$, after drawing Cash, the new probabilities will be$(Invalid,Invalid,1.0)$.
You need the cars of Rivals. So, you need to find the expected number of races that you must play in order to draw a pink slip.
Input
The first line of input contains a single integer $t$ ($1\leq t\leq 10$) — the number of test cases.
The first and the only line of each test case contains four real numbers $c$, $m$, $p$ and $v$ ($0 \lt c,m,p \lt 1$, $c+m+p=1$, $0.1\leq v\leq 0.9$).
Additionally, it is guaranteed that each of $c$, $m$, $p$ and $v$ have at most $4$ decimal places.
Output
For each test case, output a single line containing a single real number — the expected number of races that you must play in order to draw a Pink Slip.
Your answer is considered correct if its absolute or relative error does not exceed $10^{-6}$.
Formally, let your answer be $a$, and the jury's answer be $b$. Your answer is accepted if and only if $\frac{|a - b|}{\max{(1, |b|)}} \le 10^{-6}$.
Note
For the first test case, the possible drawing sequences are:
Pwith a probability of$0.6$;CPwith a probability of$0.2\cdot 0.7 = 0.14$;CMPwith a probability of$0.2\cdot 0.3\cdot 0.9 = 0.054$;CMMPwith a probability of$0.2\cdot 0.3\cdot 0.1\cdot 1 = 0.006$;MPwith a probability of$0.2\cdot 0.7 = 0.14$;MCPwith a probability of$0.2\cdot 0.3\cdot 0.9 = 0.054$;MCCPwith a probability of$0.2\cdot 0.3\cdot 0.1\cdot 1 = 0.006$.
So, the expected number of races is equal to $1\cdot 0.6 + 2\cdot 0.14 + 3\cdot 0.054 + 4\cdot 0.006 + 2\cdot 0.14 + 3\cdot 0.054 + 4\cdot 0.006 = 1.532$.
For the second test case, the possible drawing sequences are:
Pwith a probability of$0.4$;CPwith a probability of$0.4\cdot 0.6 = 0.24$;CMPwith a probability of$0.4\cdot 0.4\cdot 1 = 0.16$;MPwith a probability of$0.2\cdot 0.5 = 0.1$;MCPwith a probability of$0.2\cdot 0.5\cdot 1 = 0.1$.
So, the expected number of races is equal to $1\cdot 0.4 + 2\cdot 0.24 + 3\cdot 0.16 + 2\cdot 0.1 + 3\cdot 0.1 = 1.86$.
样例
4
0.2 0.2 0.6 0.2
0.4 0.2 0.4 0.8
0.4998 0.4998 0.0004 0.1666
0.3125 0.6561 0.0314 0.2048
1.532000000000
1.860000000000
5.005050776521
4.260163673896
题面与样例版权归 Codeforces 及出题人所有;中文翻译由 AI 生成(CI 管线),如有出入请以原文为准。