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Guo Yangguang

2008-Jan-19 14:36 UTC

I have a question in my work,please help me!

The local commuter railroad services a number of towns in
Kiwiland.  Because of monetary concerns, all of the tracks are
''one-way.''
That is, a route from Kaitaia to Invercargill does not imply the
existence
of a route from Invercargill to Kaitaia.  In fact, even if both of these
routes do happen to exist, they are distinct and are not necessarily the
same distance!

 My problem is how to computer the number of trips between two station
with exactly some stops,for example ,A to C with exactly 4stops. In the
sample data below, there are three such trips: A to C (via B,C,D); A
to C (via D,C,D); and A to C (via D,E,B).

 For the test ,the towns are named using the first few letters of the
alphabet from A to D.  A route between two towns (A to B) with a
distance of 5 is represented as AB5.

Graph: AB5, BC4, CD8, DC8, DE6, AD5, CE2, EB3, AE7

Expected Output:

Output #7: 3
 My controller method is below,but i know it is wrong,how do i write it
to make it work?Thank you!

def exa_with_stops(s1,s2,esn)
   pair_group=find_route(s1,s2)
   for p in pair_group
     if p[1,1]==[2,1]
       $i=2+$n*2
     elsif Route.find_by_name(p[1,1]+p[2,1])
       $i=3+$n*2
     else
       $i=2+$n*2
     end
   end
   $n+=1
   if $i<esn
    for p in pair_group
     exa_with_stops(s1,s2,esn)
    end
   else $i==esn

   end
 end
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dafydd

2008-Jan-19 18:30 UTC

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Re: I have a question in my work,please help me!

Looks suspiciously like an instance of the pattern "do my thoughtworks
code review for me"

Almost word for word....


;-)
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Guo Yangguang

2008-Jan-20 07:34 UTC

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Re: I have a question in my work,please help me!

hello:
    I do not know the pattern you referenced.Can you help me to complete 
that method?
def exa_with_stops(s1,s2,esn)
   pair_group=find_route(s1,s2)
   for p in pair_group
     if p[1,1]==[2,1]
       $i=2+$n*2
     elsif Route.find_by_name(p[1,1]+p[2,1])
       $i=3+$n*2
     else
       $i=2+$n*2
     end
   end
   $n+=1
   if $i<esn
    for p in pair_group
     exa_with_stops(s1,s2,esn)
    end
   else $i==esn

   end
 end



dafydd wrote:> Looks suspiciously like an instance of the pattern "do my thoughtworks
> code review for me"
> 
> Almost word for word....
> 
> 
> ;-)
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Guo Yangguang

2008-Jan-21 07:43 UTC

head link

how to find exactly number of diffrent route for two station

hello:
 The following is my task:
 The local commuter railroad services a number of towns in
Kiwiland.  Because of monetary concerns, all of the tracks are
''one-way.''That is, a route from Kaitaia to Invercargill does
not imply
the
existence of a route from Invercargill to Kaitaia.  In fact, even if 
both of these routes do happen to exist, they are distinct and are not 
necessarily the
same distance!

 My task is how to computer the number of trips between two station
with exactly some stops,for example ,A to C with exactly 4stops. In the
sample data below, there are three such trips: A to C (via B,C,D); A
to C (via D,C,D); and A to C (via D,E,B).

 For the test ,the towns are named using the first few letters of the
alphabet from A to D.  A route between two towns (A to B) with a
distance of 5 is represented as AB5.

Graph: AB5, BC4, CD8, DC8, DE6, AD5, CE2, EB3, AE7


 I have design my method,but it works only for some situation.For 
example,the route number for A to E with exactly x stops:the result for 
1 or 2 or 3 or 4 stops is right,but for 5 or 6 or...,the result is 
wrong,they all are zero:0.
 The following are my methods.By the way,my model is Route in which i 
can get the route_name,distance,start_station,end_station.For example,AE 
route have the 
attribute:route_name="AE",distance=5,start_station="A",end_station="B".The
Route model works fine for my other method,so i did not paste the model 
code here.Please help me to find where are wrong?Thank you very much!
def exa_stops #this
    @stops=params[:exastops].to_i
   if @stops==1
     onestop_route=route_with_onestop(params[:ss1],params[:es1])
     if onestop_route
       @exa_stops_number=1
     else
       @exa_stops_number=0
     end
   else
      l=exa_with_stops(params[:ss1],params[:es1],@stops).length
      @exa_stops_number=l
    end
  end

private
  def find_route(s1,s2)
    start_routes=Route.find_all_by_start_station(s1)
    end_routes=Route.find_all_by_end_station(s2)
    middle_array=Array.new
     for s in start_routes
       for e in end_routes
        middle_array<<s.name+e.name
        end
      end
      pair_group=middle_array
    if pair_group.length !=0
     for p in pair_group
        pair_group.delete(p) if p[2,1]=="A"
     end
     return pair_group
    end
  end

  def route_with_onestop(s1,s2)
   Route.find_by_name(s1+s2)
  end

 def exa_with_stops(s1,s2,esn)

 if esn==2 || esn==3
  @exastops_array=Array.new
  @pair_group=find_route(s1,s2)
  for p in @pair_group
   if p[1,1]==p[2,1]
       @exastops_array<<2
   end
   if Route.find_by_name(p[1,1]+p[2,1])
       @exastops_array<<3
   end
     @part_of_exastops_array=Array.new
     @exastops_array.each {|e| @part_of_exastops_array<<e if e==esn}
  end
 else
   @n=1
   @exastops_array=Array.new
   @pair_group=find_route(s1,s2)
   @middle_array=@pair_group
   @exaroutes_array=Array.new
   if (esn%2)==0
     @i=esn/2
   else
     @i=(esn-1)/2
   end
   while(@n<@i)
     for m in @middle_array
      @exaroutes_array=@exaroutes_array+find_route(m[1,1],m[2,1])
     end
      for e in @exaroutes_array
       if e[1,1]==e[2,1]
        s=2+2*@n
        @exastops_array<<s
       end
       if Route.find_by_name(e[1,1]+e[2,1])
        s=3+2*@n
        @exastops_array<<s
       end
      end
      @middle_array=@exaroutes_array
      @exaroutes_array.clear
      @n+=1
   end
   if @n==@i
     @part_of_exastops_array=Array.new
     @exastops_array.each {|e| @part_of_exastops_array<<e if e==esn}
   end
 end
  return @part_of_exastops_array
end
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Guo Yangguang

2008-Jan-21 11:00 UTC

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Re: how to find exactly number of diffrent route for two station

I manage it with another method ,but i is still wrong.The code is:

def exa_stops
 exa_with_stops(params[:ss1],params[:es1],params[:stops],0)
end

private
  def find_route(s1,s2)
    start_routes=Route.find_all_by_start_station(s1)
    end_routes=Route.find_all_by_end_station(s2)
    middle_array=Array.new
     for s in start_routes
       for e in end_routes
        middle_array<<s.name+e.name
        end
      end
      pair_group=middle_array
    if pair_group.length !=0
     for p in pair_group
        pair_group.delete(p) if p[2,1]=="A"
     end
     return pair_group
    end
  end

  def route_with_onestop(s1,s2)
   Route.find_by_name(s1+s2)
  end

def exa_with_stops(s1,s2,esn,n)
 if $exastops_array.include?(esn)
  @part_of_exastops_array=Array.new
  $exastops_array.each{|e|@part_of_exastops_array<<e if e==esn}
  return @part_of_exastops_array.length
 else
  pair_group=find_route(s1,s2)
  @n=n
  for p in pair_group
   if p[1,1]==p[2,1]
    s=2+@n*2
    $exastops_array<<s
    exa_with_stops(p[1,1],p[2,1],esn,@n+1)
   elsif Route.find_by_with_name(p[1,1]+p[2,1])
    s=3+@n*2
    $exastops_array<<s
    exa_with_stops(p[1,1],p[2,1],esn,@n+1)
   else
    exa_with_stops(p[1,1],p[2,1],esn,@n+1)
   end
  end
 end
end
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Keynan Pratt

2008-Jan-21 12:15 UTC

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Re: how to find exactly number of diffrent route for two sta

You may want to start over with some heavy BDD.
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Guo Yangguang

2008-Jan-21 12:42 UTC

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Re: how to find exactly number of diffrent route for two sta

I do not know your means.Anyone can help me?

Keynan Pratt wrote:> You may want to start over with some heavy BDD.
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Keynan Pratt

2008-Jan-21 13:00 UTC

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Re: how to find exactly number of diffrent route for two sta

http://www.youtube.com/watch?v=oOFfHzrIDPk&feature=related
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Keynan Pratt

2008-Jan-21 13:08 UTC

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Re: how to find exactly number of diffrent route for two sta

You should be able to modify this pretty easily to get you the routes 
from any given starting point to any given ending point at a set 
distance.

Lets assume this is rails and not just ruby Were working with.
#
class Station < ActiveRecord::Base

  has_and_belongs_to_many :stations_ahead,
    :class_name => ''Station'',
    :foreign_key => :beginning_station_id,
    :association_foreign_key => :ending_station_id

  def find_routes(destination, distance)
    return false      if self == destination and distance > 0
    return [[ self ]]  if self == destination
    return false      if distance <= 0

    result = false
    stations_ahead.each do |station|
      sub_routes = station.find_routes(destination, distance-1)
      if sub_routes
        sub_routes.each do |sub_route|
          sub_route.push self
        end
        result = sub_ruoutes
      end
    end
    return result
  end


end


class TrainTrack < ActiveRecord::Base
#
# Has Feilds:
#  beginning_station_id
#  ending_station_id
#

end
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Guo Yangguang

2008-Jan-22 04:16 UTC

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Re: how to find exactly number of diffrent route for two sta

hello:
  Thank you!But i want to resolve this problem:the number of different 
route from one station to another station with exactly some stops.
  My model is Route in which i can get the 
route_name,distance,start_station,end_station.For example,AE route have 
the 
attribute:route_name="AE",distance=5,start_station="A",end_station="B".
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Ryan Bigg

2008-Jan-22 04:22 UTC

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Re: how to find exactly number of diffrent route for two sta

Guo,

How about setting up a table of the stations and then a table of the routes
that has a serialized field containing the ids of the stops along the way
(something like stops_id)?

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Guo Yangguang

2008-Jan-23 12:30 UTC

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Re: how to find exactly number of diffrent route for two sta

hello:
   Thank you Ryan Bigg and Keynan Pratt ,i have resolve my question.Maby 
if i modify my database table ,i can do it .I will try it.I have managed 
it in my method design in another way.Thank you!Good luck!


Ryan Bigg wrote:> Guo,
> 
> How about setting up a table of the stations and then a table of the 
> routes
> that has a serialized field containing the ids of the stops along the 
> way
> (something like stops_id)?
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Rails - Jan 2008 - I have a question in my work,please help me!

I have a question in my work,please help me!

Re: I have a question in my work,please help me!

Re: I have a question in my work,please help me!

how to find exactly number of diffrent route for two station

Re: how to find exactly number of diffrent route for two station

Re: how to find exactly number of diffrent route for two sta

Re: how to find exactly number of diffrent route for two sta

Re: how to find exactly number of diffrent route for two sta

Re: how to find exactly number of diffrent route for two sta

Re: how to find exactly number of diffrent route for two sta

Re: how to find exactly number of diffrent route for two sta

Re: how to find exactly number of diffrent route for two sta