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  1.     exp = '1+(2-3)/(4*5)'
  2.     rpn = []
  3.     stack = []
  4.     operator = {
  5.     '(' => 0,
  6.     '+' => 1,
  7.     '-' => 1,
  8.     '*' => 2,
  9.     '/' => 2,
  10.     }
  11.  
  12.     def isdigit(c)
  13.     if c =~ /[0-9]/
  14.     return true
  15.     end
  16.     return false
  17.     end
  18.  
  19.     exp.each_char do |e|
  20.     if isdigit(e)
  21.     rpn << e
  22.     next
  23.     end
  24.     if e.class == String
  25.     case e
  26.     when ')'
  27.     while stack[-1] != '('
  28.     rpn << stack.pop
  29.     end
  30.     stack.pop
  31.     next
  32.     when '('
  33.     stack << e
  34.     next
  35.     end
  36.     if stack != []
  37.     while operator[stack[-1]] >= operator[e]
  38.     rpn << stack.pop
  39.     if stack == []
  40.     break
  41.     end
  42.     end
  43.     end
  44.     stack << e
  45.     end
  46.     end
  47.  
  48.     while stack.length != 0
  49.     rpn << stack.pop
  50.     end
  51.  
  52.     rpn.each do |e|
  53.     print "#{e} "
  54.     end
  55.     print "\n"
Success #stdin #stdout 0.01s 7420KB
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1 2 3 - 4 5 * / +
https://ideone.com/xovDW1
language:
Ruby (ruby 2.5.5)
created:
10 years ago
visibility:
public

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