Created
September 19, 2012 05:45
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Find Missing Number
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| # Setup an array of 99 numbers between 1 and 100, randomly sorted | |
| @numbers = (1..1_000_000).to_a.shuffle | |
| @numbers.delete_at(rand(1_000_000)) | |
| def sort_find | |
| sorted = @numbers.sort | |
| sorted.each_with_index do |n, i| | |
| next if n == sorted[i-1] + 1 || n == 1 | |
| return n-1 | |
| end | |
| end | |
| def inject_find | |
| (1..1_000_000).inject(&:+) - @numbers.inject(&:+) | |
| end | |
| def new_array_find | |
| new_array = [] # Array.new(1_000_000) | |
| @numbers.each { |n| new_array[n-1] = n } | |
| new_array.index(nil) + 1 | |
| end | |
| t1 = Time.now | |
| sort_find | |
| t2 = Time.now | |
| p "Time to execute sort_find: #{t2 - t1}" | |
| p "Found the missing number: #{@numbers.index(sort_find) == nil}" | |
| t3 = Time.now | |
| inject_find | |
| t4 = Time.now | |
| p "Time to execute inject_find: #{t4 - t3}" | |
| p "Found the missing number: #{@numbers.index(inject_find) == nil}" | |
| t5 = Time.now | |
| new_array_find | |
| t6 = Time.now | |
| p "Time to execute new_array_find: #{t6 - t5}" | |
| p "Found the missing number: #{@numbers.index(new_array_find) == nil}" | |
| case [(t6-t5),(t4-t3),(t2-t1)].min | |
| when t2-t1 then fastest = :sort_find | |
| when t4-t3 then fastest = :inject_find | |
| when t6-t5 then fastest = :new_array_find | |
| end | |
| p "-----------------\nFASTEST METHOD: #{fastest}" |
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