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PRLCM - Personal LCM |
We have an integer sequence of length N: A0, A, ... AN−1.
Find the following sum:
$\displaystyle\sum^{N-2}_{i=0}{\sum^{N-1}_{j=i+1}{lcm(Ai, Aj)}}$
(Note: lcm(a, b) denotes the least common multiple of a and b)
Since the answer may be enormous, compute it modulo 998244353
Constraints
- 1 ≤ N ≤ 2 * 105
- 1 ≤ A
≤ 106 - All values in input are integers.
Input
First line of input will be consist of a single N, number of elements.
In next line you will get N space separated integers: A0 A1 A2 A3 A4 ... AN-1
Output
Print the sum modulo 998244353.
Example
Input: 3 2 4 6 Output: 22
Explanation
lcm(2, 4) + lcm(2, 6) + lcm(4, 6) = 4 + 6 + 12 = 22.
Added by: | Amit |
Date: | 2020-06-25 |
Time limit: | 1s |
Source limit: | 50000B |
Memory limit: | 1536MB |
Cluster: | Cube (Intel G860) |
Languages: | All |
hide comments
2020-07-13 17:21:53
TLE at case 12 |
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2020-07-11 21:09:32
https://www.quora.com/How-do-I-find-the-sum-of-the-lowest-common-multiples-LCM-of-each-pair-of-integers-from-n-given-positive-integers refer this Last edit: 2020-07-12 16:22:36 |
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2020-07-09 05:46:27
Is there any editorial about this problem? Can someone share any link? |
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2020-06-27 11:22:24
is there a faster method to calculate gcd or there is a trick ????????? |
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2020-06-26 13:28:56
@iseng_cuk It's total running time. |
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2020-06-26 12:26:42
the time limit is 1s but the accepted solution times are 1.90 and 6.42. are those numbers in milliseconds? Author Reply: There are 15 testcases, and for each testcase your program will get 1 sec. So I think you will get 15 sec in total. oh, I see. Last edit: 2020-06-28 12:47:45 |
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2020-06-26 02:23:00 [Rampage] Blue.Mary
The input data contains at least one test case with a[i] > 100000; at least one test case with n > 20000. Please check. Edit: My AC solution assumes n <= 200000 and a[i] <= 1000000. Reply : Updated. Last edit: 2020-06-26 05:50:16 |