On 2/23/15 3:21 PM, Charles wrote:
For the uninitiated, Code Golf is producing the correct answer to a
question with minimal syntax (whitespace included). I found a couple
questions on HackerRank, which allows D compilation. So far there's only
two entries for D (mine and another) for the first problem.
Here's the problem:
In Calculus, the Leibniz formula for π is given by:
1 - 1/3 + 1/5 - 1/7 + 1/9 - ... = pi/4
You will be given an integer n. Your task is to print the summation of
the Leibniz formula up to the nth term of the series correct to 15
decimal places.
Input Format
The first line contains the number of test cases (T) which is less than
100. Each additional line is a test case for a positive integer value
(p) less than 10^7.
Sample Input
2
10
20
Output Format
Output T lines, with each line containing the summation up to nth term.
Sample Output
0.760459904732351
0.772905951666960
Scoring
This is a code golf question. The goal is to write a solution with as
little code as possible. A correct submission with a source code of X
characters will receive the following score:
maxScore * (300 - X)/300
Any correct code longer than 300 characters will receive a score of
maxScore * 0.001.
MaxScore is the maximum score attainable for the problem.
Note that whitespace is also treated as a character.
My solution (150 characters, 15 points):
void main(){import std.stdio;int t,n;readf("
%d",&t);while(t--){readf(" %d",&n);real
a=0,i=0;for(;i<n;i++)a+=(i%2?-1:1)/(i+i+1);writefln("%.15f",a);}}
Link to problem site: https://www.hackerrank.com/challenges/leibniz
Anyone care to do better? :)
I didn't beat your score, but I did it with ranges (full character count
was 174):
stdin.readln();
foreach(x; stdin.byLine)
writefln("%0.15f", map!(a =>
(a&1?-1:1)/(2.0*a+1))(iota(x.to!int)).sum);
I think if I didn't have to import so many things, I would have done
much better :)
-Steve
