Simplex

simplex.rb

def parseInput(a,flag)
    def handleOne(x)
        if x.length == 1 or x =~ /^\+[a-z]$/
            1
        elsif x =~ /^-[a-z]$/
            -1
        else
            x.chop.to_i
        end
    end
    symbols=Hash.new
    if flag == 'o'
        if a =~ /^[\+|-]?\d*[a-z]{1}([\+|-]\d*[a-z]{1})+$/
            res = a.scan(/[\+|-]?\d*[a-z]{1}/)
        else 
            return false
        end
    end
    
    if flag == 'c'
        if a=~ /^[\+|-]?\d*[a-z]{1}([\+|-]\d*[a-z]{1})+=\d+$/
            res = a.scan(/[\+|-]?\d*[a-z]/)
        else return false
        end 
        symbols['='] = a.split('=').last.to_i
    end
    mod=Hash['o',-1,'c',1]
    for i in res
        last=i.split('').last
        if symbols.has_key?(last)

            symbols[last]+=handleOne(i)*mod[flag]
        else
            symbols[last]=handleOne(i)*mod[flag]
        end
    end
    symbols
end
#puts 'Enter Objective'
#a = gets.chomp 
#puts parseInput(a,'o')
#while !parseInput(a,'o')
#    puts 'Enter Objective'
#    a=gets.chomp
#end
obj=parseInput('3x+2y+5z','o')
#puts 'Enter Contraints'
#a = gets.chomp
#cons=[]
#while !a.empty?
#    parse=parseInput(a,'c')
#    puts parse ? cons << parse : 'Invalid Cons' 
#    a = gets.chomp
#end
cons=['2x+2y+5z=60','4x+y+2z=56'].map{|x| parseInput(x,'c')}
nCons=cons.size
headings = obj.keys.concat(cons.map(&:keys).flatten).uniq
headings.concat((0...nCons).map{|x| "S%s" % x}) 
rows = Hash.new
rows[0] = Hash['P',1]
headings.each{|x| rows[0][x] =  obj.key?(x) ? obj[x] : 0}
rown=0
cons.each{|item| rown+=1
            rows[rown]=Hash['P',0]
            headings.each{|x| rows[rown][x] =  cons[rown-1].key?(x) ? cons[rown-1][x] : 0}
            rows[rown]['S%d' % (rown-1)] = 1
        }
puts rows
while !headings.select{|x| x.match(/^[a-z]$/) && rows[0][x]<0}.empty?
    #select=rows[0].min{|a,b| rows[0][b] <=> rows[0][a]}
    select = rows[0].sort_by(&:last).first[0]
    puts select
    comp = (1..nCons).min_by{|x| rows[x][select] > 0 ? (rows[x]['=']*1.0)/rows[x][select] : 1.0/0.0}
    pivot = rows[comp][select]*1.0
    rows[comp].each{|key,value| rows[comp][key] = value/pivot}
    (0..nCons).find_all{|x| x != comp}.each{|r| factor = rows[r][select]*(-1)
                                                        headings.each{|h| rows[r][h] = rows[r][h]+(rows[comp][h]*factor)}}
    
end
puts rows.each(&:inspect)