There is n integer elements. Choose k elements then calculate their GCD, call result X.
What is maximal value of X?
k<=n<=3000, k<=100, elements in range 1..10^10.
Example:
3 2
120
36
100
Sample output
20
# | User | Rating |
---|---|---|
1 | ecnerwala | 3649 |
2 | Benq | 3581 |
3 | orzdevinwang | 3570 |
4 | Geothermal | 3569 |
4 | cnnfls_csy | 3569 |
6 | tourist | 3565 |
7 | maroonrk | 3531 |
8 | Radewoosh | 3521 |
9 | Um_nik | 3482 |
10 | jiangly | 3468 |
# | User | Contrib. |
---|---|---|
1 | maomao90 | 174 |
2 | awoo | 164 |
3 | adamant | 162 |
4 | TheScrasse | 159 |
5 | nor | 158 |
6 | maroonrk | 156 |
7 | -is-this-fft- | 151 |
8 | SecondThread | 147 |
9 | orz | 146 |
10 | pajenegod | 145 |
There is n integer elements. Choose k elements then calculate their GCD, call result X.
What is maximal value of X?
k<=n<=3000, k<=100, elements in range 1..10^10.
Example:
3 2
120
36
100
Sample output
20
Name |
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These constraints are in a very gray area, it really depends on the time limit. So depending on the limit you may or may not be able to:
Factor each number: Sieve of Eratosthenes + 3000 * (primes below 10 ^ 5) = 3000 * 10000; Generate divisors of each number in O(divisor_count). Divisor_count is at most 2300. Keep a frequency table for the divisors and just select the biggest one that's over k.
Just a first thought. It's a fragile solution, but it may very well work. Again, the constraints are too fuzzy. Will look for something cleaner and smarter though :).
If I correctly understood your solution it wouldn't work because the gcd can be a composite number instead of a prime.
I take in account all divisors, composite or not. The factoring into primes part is only so you can generate the divisors of a number quickly, instead of trying each number up to 10 ^ 5.
Thank you, I understood.
ez
gg easy FTFY