IEEEBGAM - The Ball Game

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Taru and Hanaku play a ball game. The game is played with N white balls, N black balls and N boxes. Hanaku chooses one box randomly and one ball from it randomly. Taru has to arrange the balls in such a way that the probability of Hanaku choosing a White ball is maximised. None of the boxes after the arrangement should be empty. Your task is to find that maximum probability.


The first line contains the number of test cases (T) followed by T lines each an integer N.


For each test case output the maximum probability of getting a white ball which is possible with an arrangement for the above configuration. Print the answer rounded to 8 decimal places.


T <= 20
N <= 1000


Sample Input:

Sample Output:

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pandey101299: 2019-02-10 12:25:34

So easy problem Ac in one go....

Last edit: 2019-02-10 12:26:04
sanchit_aga: 2019-01-08 17:55:46

Keep an eye on how you print your decimals, for example 0.66666667 will give AC while 0.66666666 will give WA if probability is 2/3. This cost me a WA.

sanjay5797: 2017-06-23 15:40:35

my 150th!!!...AC in one go....
should be moved to tutorials!!

iharsh234: 2015-12-31 18:42:18

not classical one!
move to tutorials

adi_tri: 2015-08-13 21:31:58

should be move to tutorials...

cosmopoliton: 2015-03-20 06:38:31

dam easy once you get the right relation

Lehar: 2015-02-21 11:32:11

AC after a month! :D

Indian Cyber Army (IndiShell): 2015-02-05 14:28:32

AC in 1st go .. :)
[Spoiler Removed]

re(vamsi): please don't comment on every other problem you solve unless it is important(related to problem/IO formatting) or the problem is too good

Last edit: 2015-02-05 16:24:21
freaker: 2014-12-20 07:37:07

1 line code in perl ...

Aditya Joshi: 2014-10-03 10:03:34

Be careful with the formatting of your answer. In Java use the DecimalFormat class to format your answer to 8 decimal places and remember to append a "0" to the start since DecimalFormat will return strings of the form .324 etc.

Added by:Saransh Bansal
Time limit:0.100s
Source limit:50000B
Memory limit:1536MB
Cluster: Cube (Intel G860)
Languages:All except: ASM64