NAJPWG - Playing with GCD
Tanmoy recently learn about Euclid gcd algorithm. This algorithm looks like:
gcd(a, b): if (b == 0): return a return gcd(b, a % b)
Now he want to find out how many pair (x, y) can be possible in range N, which gcd is greater than 1. Here pair (x, y) and (y, x) consider as same pair. 1<=x, y<=N.
He can find out it small number easily but for a large number its really hard to find out. Now he needs your help. Write a programme that find out number of such pair.
Input
Input start with an integer number T ( ≤ 10^5), which is number of test cases.
Each test case contain a integer N (1 ≤ N ≤ 10^5).
Output
For each case, print case number and desired answer
Sample
Input: 2 3 4 Output: Case 1: 2 Case 2: 4
hide comments
awhfahim:
2022-06-11 22:06:04
little bit tricky.... Last edit: 2022-06-11 22:06:37 |
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ayu_031201:
2022-01-07 09:01:34
observation on phi + prefix sum :) |
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mursaleen:
2020-08-05 08:00:52
About output format : There's no blank line before the first test case. And there's a space between "Case" and the case number, and between the colon (':') and the answer. |
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dhruv788:
2020-07-16 18:16:04
Beware of the output format , There is no next line before the test case 1
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selfcoder24:
2019-07-13 17:29:24
Concept of Phi and observation. Be extra sure on the output format :-) |
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immim:
2018-12-22 06:03:14
Phi Sieve + Cumulative sum.....See output format. :) |
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m2do:
2018-03-12 19:36:09
Euler Totient + DP <3 |
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itachi_2016:
2018-01-02 15:27:33
Very easy ! |
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chetan4060:
2018-01-01 11:45:39
ac in second go:-)
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mahilewets:
2017-09-08 14:38:53
Sudden AC after realizing I can precalc for all possible queries |
Added by: | Najmuzzaman |
Date: | 2014-10-31 |
Time limit: | 0.5s |
Source limit: | 50000B |
Memory limit: | 1536MB |
Cluster: | Cube (Intel G860) |
Languages: | All except: ASM64 |