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Fixes the 'planets align' condition of select.last vs reverse.detect #122

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Fixes the 'planets align' condition of select.last vs reverse.detect #122

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15 changes: 15 additions & 0 deletions code/enumerable/select-last-vs-reverse-detect.rb
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Original file line number Diff line number Diff line change
Expand Up @@ -3,15 +3,30 @@
ARRAY = [*1..100]

def fast
# "It just happens to line up" case
ARRAY.reverse.detect { |x| (x % 10).zero? }

# "Middle of the road" case
# ARRAY.reverse.detect { |x| ((x % 10) == 60) }

# "Worst Case" scenario
# ARRAY.reverse.detect { |x| x == 1 }
end

def slow
# "It just happens to line up" case
ARRAY.select { |x| (x % 10).zero? }.last

# "Middle of the road" case
# ARRAY.select { |x| ((x % 10) == 60) }.last

# "Worst Case" scenario
# ARRAY.select { |x| x == 1 }.last
end

Benchmark.ips do |x|
x.report('Enumerable#reverse.detect') { fast }
x.report('Enumerable#select.last') { slow }
x.compare!
end