Fastest method to see if all elements in an array have a particular value
I need a very fast way to determine if an array consits only of integers with the value of 9 . Here is my current solution:
input = [9,9,9,9,9,9,9,9,9,9,9,9]
input.uniq == [9]
Can you do it faster?
require 'benchmark'
n = 50000
Benchmark.bm do |x|
x.report do
n.times do
input = [9,9,9,9,9,9,9,9,9,9,9,9]
input.uniq == [9]
end
end
x.report do
n.times do
input = [9,9,9,9,9,9,9,9,9,9,9,9]
input.delete 9
input == []
end
end
x.report do
n.times do
input = [9,9,9,9,9,9,9,9,9,9,9,9]
input.count(9)==input.size
end
end
x.report do
n.times do
input = [9,9,9,9,9,9,9,9,9,9,9,9]
input.select{|x| x != 9}.empty?
end
end
x.report do
n.times do
input = [9,9,9,9,9,9,9,9,9,9,9,9]
input.detect { |i| i != 9 }.nil?
end
end
x.report do
n.times do
input = [9,9,9,9,9,9,9,9,9,9,9,9]
input.all?{|x| x == 9}
end
end
end
it a benchmark for the answers above and some mine
user system total real
uniq 0.313000 0.000000 0.313000 ( 0.312500)
delete 0.140000 0.000000 0.140000 ( 0.140625)
count 0.079000 0.000000 0.079000 ( 0.078125)
select 0.234000 0.000000 0.234000 ( 0.234375)
detect 0.234000 0.000000 0.234000 ( 0.234375)
all? 0.219000 0.000000 0.219000 ( 0.218750)
if input = [1]+[9]*9 :
user system total real
uniq 0.328000 0.000000 0.328000 ( 0.328125)
delete 0.188000 0.000000 0.188000 ( 0.203125)
count 0.187000 0.000000 0.187000 ( 0.218750)
select 0.281000 0.016000 0.297000 ( 0.296875)
detect 0.203000 0.000000 0.203000 ( 0.203125)
all? 0.204000 0.000000 0.204000 ( 0.203125)
if input = [9]*9 + [1] :
user system total real
uniq 0.313000 0.000000 0.313000 ( 0.328125)
delete 0.187000 0.000000 0.187000 ( 0.187500)
count 0.172000 0.000000 0.172000 ( 0.187500)
select 0.297000 0.000000 0.297000 ( 0.312500)
detect 0.313000 0.000000 0.313000 ( 0.312500)
all? 0.281000 0.000000 0.281000 ( 0.281250)
if input = [1,2,3,4,5,6,7,8,9] :
user system total real
uniq 0.407000 0.000000 0.407000 ( 0.406250)
delete 0.125000 0.000000 0.125000 ( 0.125000)
count 0.125000 0.000000 0.125000 ( 0.125000)
select 0.218000 0.000000 0.218000 ( 0.234375)
detect 0.110000 0.000000 0.110000 ( 0.109375)
all? 0.109000 0.000000 0.109000 ( 0.109375)
You have a few options:
>> input.count(9)==input.size
=> true
or
>> input.select{|x| x != 9}.empty?
=> true
or the solution you had above.
这会循环数组并在找到非九的时候中断（返回false）。
[9,9,9,9,9,9,9,9,9,9,9,9].all?{|x| x == 9} # => true
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