GOV04 - Quadratic primes
Euler published the remarkable quadratic formula:
n² + n + 41
It turns out that the formula will produce 40 primes for the consecutive values n = 0 to 39. However, when n = 40, 402 + 40 + 41 = 40(40 + 1) + 41 is divisible by 41.
Using computers, the incredible formula n² - 79n + 1601 was discovered, which produces 80 primes for the consecutive values n = 0 to 79. The absolute product of the
coefficients, 79 and 1601, is 126479.
We are interested in producing better quadratic formulas.( which produces more prime numbers )
Considering quadratics of the form:
n² + an + b, where |a| <= R and |b| <= R
( Your input will be the value of R )
where |n| is the modulus/absolute value of n
e.g. |11| = 11 and | - 4| = 4
Find a and b, for the quadratic expression that produces the maximum number of primes for consecutive values of n, starting with n = 0.
If two different values of n produces same prime, then we consider those primes as different (i.e. we count them twice) -- look at example.
Remember |a| <= R and |b| <= R
If you get multiple answers, choose the one having smallest value of a. Even then, if you get multiple answers, choose the equation having smallest value of b.
Input
First line of input contains an integer 't' representing the number of test cases. Then 't' lines follows.
Each line contains an integer R.
t<=8000
R<=10000
Output
Output should be of the format:
Integer 1<space>@<space>Integer2
Integer 1: Number of primes equation n2+an+b produces for consecutive value of n, starting from n=0.
Integer 2: absolute product of the coefficients, a and b.
Output of each test case should be on separate line.
Scoring
Lesser your fingers work, better it is. :-)
(Minimize your source code length)
Example
Input: 2
41
5 Output: 41 @ 41
5 @ 5
Explanation:
case 1: a=-1 b=41
case 2: a=-1 b=5 ( Here n=0 and n=1 produces same prime 5, but we will count it twice)
hide comments
Aditya Pande:
2013-06-16 21:22:37
used up all optimizations and got it in 0.00 seconds. |
|
:-):
2013-04-12 16:31:48
@nice problem
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Added by: | Govind Lahoti |
Date: | 2013-04-10 |
Time limit: | 1s-2s |
Source limit: | 10000B |
Memory limit: | 1536MB |
Cluster: | Cube (Intel G860) |
Languages: | All except: ASM32-GCC ASM64 MAWK BC C-CLANG NCSHARP CPP14 CPP14-CLANG COBOL COFFEE D-CLANG D-DMD DART ELIXIR FANTOM FORTH GOSU GRV JS-MONKEY JULIA KTLN NIM OBJC OBJC-CLANG OCT PICO PROLOG PYPY PYPY3 R RACKET RUST CHICKEN SQLITE SWIFT UNLAMBDA VB.NET |
Resource: | Project euler |