BALLSUM - Ball sum
You have a bag filled with N balls. Each ball has a distinct number from 1 to N printed on it. All the numbers are distinct. You withdraw two balls from the bag and take their sum. You need to calculate the probability that the sum is not greater than the given number K (≤ N). The answer should be displayed in the form of p/q (except when the answer is 0 or 1.)
Input
Input consists of various test cases. Each test case consist of two integer inputs, N and K. (0 ≤ K ≤ N ≤ 1000000000) The program stops taking input when N and K equals -1.
Output
Output the result in the form of p/q (except when the answer is 0 or 1.)
Example
Input: 3 2 100 5 10 6 -1 -1 Output: 0 2/2475 2/15
hide comments
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nadstratosfer:
2017-09-21 02:15:30
Print newline after last result else WA.
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mahilewets:
2017-09-03 09:30:51
Some people saying you need an O(log(M)) per query algorithm
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aman_9899:
2017-07-03 22:10:43
check for edge cases ..!!!
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ayushgupta1997:
2017-05-29 13:26:45
nice problem :) use pen and paper...check for odd and even values of k |
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shubhisri:
2017-01-13 17:54:20
I am getting tle, can anyone help me? |
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kass_97:
2016-12-30 12:30:37
Took paper and pen, did some thinking and bingo....AC |
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mrx:
2016-12-11 05:57:12
I don't know why I got TLE. I calculated p and q using maths in O(1) and their gcd using recursion and I used C :/
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kira28:
2016-12-08 21:04:22
#elementary_school_maths
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rrm_2016:
2016-11-26 21:27:40
Lol...that "/" in "p/q" made me submit one wrong solution...otherwise this is a very eazzyy problem..just high school combinatorics Last edit: 2016-11-26 21:27:58 |
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binari:
2016-08-01 22:09:33
Why my code gives wa, I think my code works correct in every status, by the way what should be written when n=0 and k=0 or n=1,k=1 (inputs like this)? |
| Added by: | Prateek Agarwal |
| Date: | 2015-12-15 |
| Time limit: | 1s |
| Source limit: | 50000B |
| Memory limit: | 1536MB |
| Cluster: | Cube (Intel G860) |
| Languages: | All except: ASM64 GOSU JS-MONKEY |
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