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
hide comments
:D:
2018-10-23 01:06:16
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:
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waffl3:
2016-12-06 14:15:17
getting tle -_-
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jinxer:
2016-06-12 16:15:24
getting TLE..any hint ???
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ashish kumar:
2016-05-05 05:36:49
What is the range of integer ??? |
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jarnura:
2016-04-27 14:41:39
2 is a square free number or not? |
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Samuel Nacache:
2016-04-27 04:43:46
@lumaere yes, it's the product of all the primes less than 50 |
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lumaere:
2016-04-17 01:59:55
Is there an upperbound on the size of each number? |
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vivekrnj:
2016-04-07 19:48:26
me getting TLE..hint!
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Emruz Hossain:
2016-04-05 19:08:02
@rainy Jain: Output of your test case is 89 |
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rainy jain :
2016-04-05 04:53:41
What will be the output in this case:
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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 |