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TIP1 - Totient in permutation (easy) |
In number theory, Euler's totient (or PHI function), is an arithmetic function that counts the number of positive integers less than or equal to a positive integer N that are relatively prime to this number N.
That is, if N is a positive integer, then PHI(N) is the number of integers K for which GCD(N, K) = 1 and 1 ≤ K ≤ N. We denote GCD the Greatest Common Divisor. For example, we have PHI(9)=6.
Interestingly, PHI(87109)=79180, and it can be seen that 87109 is a permutation of 79180.
Input
The input begins with the number T of test cases in a single line. In each of the next T lines there are an integer M.
Output
For each given M, you have to print on a single line the value of N, for which 1 < N < M, PHI(N) is a permutation of N and the ratio N/PHI(N) produces a minimum. If there's several answers output the greatest, or if need, "No solution." without quotes. Leading zeros are not allowed for integers greater than 0.
Example
Input: 3 22 222 2222 Output: 21 63 291
Explanations : For the first case, in the range ]1..22[, the lonely number n for which phi(n) is in permutations(n) is 21, (we have phi(21)=12). So the answer is obviously 21. For the second case, in the range ]1..222[, there's two numbers n for which phi(n) is in permutations(n), we have phi(21)=12 and phi(63)=36. But as 63/36 is equal to 21/12, we're taking the greater : 63. For the third case, in the range ]1..2222[, there's four numbers n for witch phi(n) is in permutations(n), phi(21)=12, phi(63)=36, phi(291)=192 and phi(502)=250. Within those solutions 291/192 is the minimum, we output 291.
Constraints
1 < T < 10^5 1 < M < 10^7
Code size limit is 10kB ; less than 500B of python3 code can get AC under 2s. After that you may try TIP2. @Speed addicts : my C code ran in 0.02s, and my fastest python3.2 code ran in 1.21s, (0.90s in py2.7)
Edit 2017-02-11, after compiler updates. My old C code ends in 0.00s, my old Python code ends in 0.05s !!!
Added by: | Francky |
Date: | 2013-01-06 |
Time limit: | 1.399s |
Source limit: | 10000B |
Memory limit: | 1536MB |
Cluster: | Cube (Intel G860) |
Languages: | All except: ASM64 |
Resource: | Extension of Project Euler n°### |
hide comments
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2023-01-28 06:22:01
I think this statement is wrong "if N is a positive integer, then PHI(N) is the number of integers K for which GCD(N, K) = 1 and 1 ≤ K ≤ N." It should be: if N is a positive integer, then PHI(N) is the number of integers K, in which each number x has this property GCD(N, x) = 1 and 1 ≤ x ≤ N. correct it, please. =(Francky)=> The first statement is correct. We ask for a cardinal : how many numbers are such that... Any number K who satisfies the rule is counted. The question is : "how many such K ?" I hope you'll enjoy the exercise and future developments. Last edit: 2023-02-16 21:37:37 |
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2020-08-19 01:50:54
Can anyone plz tell me the approach for this problem? |
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2020-08-12 17:21:30
please anyone tell me what are the approach to solve this problem?? |
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2019-12-20 18:41:51
anyone please help me to find the logic of the problem |
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2019-07-14 16:21:49
@Francky Can you please check my code is getting WA ?? Submission ID 24075839 Finally solved it mind that n<m Last edit: 2019-07-14 17:09:27 |
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2019-01-09 08:56:13
Thanks @Francky. Mind n<m |
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2019-01-08 12:25:41
@Francky Can you please check my code. I am getting right answers for every test case on Spoj Toolkit. =(Francky)=> S-Toolkit isn't official and maybe have wrong or incomplete answers... You have wrong answers for small inputs. Last edit: 2019-01-08 15:48:33 |
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2017-02-12 15:36:17 Francky
Congratulations to Tjandra for being the lonely (for now) Python solver. Here, there's a little challenge. |
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2016-03-20 22:47:29 DHEERAJ KUMAR
@Francky do i have WA for many inputs? submission id 16561400 |
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2015-10-03 21:50:00 .:frUstrAteD:.
@Francky Can you please check my code is getting WA =(Francky)=> You have WA for only some small values. Good luck. Last edit: 2015-10-12 21:02:36 |