Tim Varley Tim Varley

Euler 009 ruby Solution

Special Pythagorean triplet
Dec 11, 2015
3 minute read

Problem

https://projecteuler.net/problem=9

A Pythagorean triplet is a set of three natural numbers,

\[a < b < c\]

for which,

\[a^2 + b^2 = c^2\]

For example:

\[3^2 + 4^2 = 9 + 16 = 25 = 5^2\]

There exists exactly one Pythagorean triplet for which

\[a + b + c = 1000\]

Find the product \(abc \).

Answer: 31875000 (a:200 b:375 c:425)

Solution

euler009.rb

#!/usr/bin/env ruby
def pyg(limit)
  # We can limit the range of a and b because of the following requirements:
  # a < b < c
  # a + b + c = 1000
  (1..limit / 3).each do |a|
    (a..limit / 2).each do |b|
      c = 1000 - b - a
      return (a * b * c) if (a * a) + (b * b) == (c * c)
    end
  end
end

puts pyg(1000) if __FILE__ == $PROGRAM_NAME

See Also

# cpp go java php ruby rust javascript
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# cpp ruby
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