9674: ABC184 —— D - increment of coins
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Description
We have a bag containing $A$ gold coins, $B$ silver coins, and $C$ bronze coins.
Until the bag contains $100$ coins of the same color, we will repeat the following operation:
Operation: Randomly take out one coin from the bag. (Every coin has an equal probability of being chosen.) Then, put back into the bag two coins of the same kind as the removed coin.
Find the expected value of the number of times the operation is done.
Until the bag contains $100$ coins of the same color, we will repeat the following operation:
Operation: Randomly take out one coin from the bag. (Every coin has an equal probability of being chosen.) Then, put back into the bag two coins of the same kind as the removed coin.
Find the expected value of the number of times the operation is done.
Input
Input is given from Standard Input in the following format:
```
$A$ $B$ $C$
```
```
$A$ $B$ $C$
```
Output
Print the expected value of the number of times the operation is done. Your output will be accepted if its absolute or relative error from the correct value is at most $10^{-6}$.
Constraints
- $0 \leq A,B,C \leq 99$
- $A+B+C \geq 1$
- $A+B+C \geq 1$
Sample 1 Input
99 99 99
Sample 1 Output
1.000000000
No matter what coin we take out in the first operation, the bag will contain 100 coins of that kind.
Sample 2 Input
98 99 99
Sample 2 Output
1.331081081
We will do the second operation only if we take out a gold coin in the first operation. Thus, the expected number of operations is $2×\frac{98}{98+99+99}+1×\frac{99}{98+99+99}+1×\frac{99}{98+99+99}=1.331081081…$
Sample 3 Input
0 0 1
Sample 3 Output
99.000000000
Each operation adds a bronze coin.
31 41 59
91.835008202