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NGCD - NO GCD |
You are given N (1 <= N <= 100000) integers. Each integer is square free (meaning it has no divisor which is a square number except 1) and all the prime factors are less than 50. You have to find out the number of pairs are there such that their gcd is 1 or a prime number. Note that (i, j) and (j, i) are different pairs if i and j are different.
Input
The first line contains an integer T (1 <= T <= 10), the number of tests. Then T tests follows. First line of each tests contain an integer N. The next line follows N integers.
Output
Print T lines. In each line print the required result.
Example
Input: 1 3 2 1 6 Output: 8
Explanation
- gcd(1, 2) = 1
- gcd(2, 1) = 1
- gcd(2, 6) = 2, a prime number
- gcd(6, 2) = 2, a prime number
- gcd(1, 6) = 1
- gcd(6, 1) = 1
- gcd(2, 2) = 2, a prime number
- gcd(1, 1) = 1
So, total of 8 pairs.
Problem Setter: Nafis Sadique, Jahangirnagar University
Added by: | Alim |
Date: | 2016-04-01 |
Time limit: | 2s |
Source limit: | 50000B |
Memory limit: | 1536MB |
Cluster: | Cube (Intel G860) |
Languages: | All except: ASM64 GOSU JS-MONKEY |
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2018-10-23 01:06:16 :D
Very good problem. It's not really about factorization and underlying problem is fairly difficult. It's also properly described, but I will still sum up answers to question in the comments: Re jarnura: Square free - not divisible by any square of an integer. 2 is square free (divisors 1 and 2). 100 is not square free (divisible by 25=5*5), as well as 27 (divisible by 9=3*3). Re ashish kumar: Description correctly specifies the integer limit for input numbers. Just read first paragraph carefully. Re jinxer: Answer for "1\n 2\n 1 1" is 4 because bcd(1,1)=1 so all possible pairs should be counter: (1,1) (1,2), (2,1), (2,2) |
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2016-12-06 14:15:17
getting tle -_- ... ... i don't know Euclidean algorithm, maybe btw. please help \(0_0)/ Last edit: 2016-12-06 14:19:32 |
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2016-06-12 16:15:24
getting TLE..any hint ??? and how is the output is 4 for the INPUT: 1 2 1 1 |
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2016-05-05 05:36:49 ashish kumar
What is the range of integer ??? |
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2016-04-27 14:41:39
2 is a square free number or not? |
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2016-04-27 04:43:46 Samuel Nacache
@lumaere yes, it's the product of all the primes less than 50 |
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2016-04-17 01:59:55
Is there an upperbound on the size of each number? |
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2016-04-07 19:48:26
me getting TLE..hint! |
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2016-04-05 19:08:02 Emruz Hossain
@rainy Jain: Output of your test case is 89 |
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2016-04-05 04:53:41 rainy jain
What will be the output in this case: 1 10 1 2 3 33 77 51 2 77 77 1 |