Question

Greetings code-gurus!

I am writing an algorithm that connects, for instance node_A of Region_A with node_D of Region_D. (node_A and node_D are just integers). There could be 100k+ such nodes.

Assume that the line segment between A and D passes through a number of other regions, B, C, Z . There will be a maximum of 20 regions in between these two nodes.

Each region has its own properties that may vary according to the connection A-D. I want to access these at a later point of time.

I am looking for a good data structure (perhaps an STL container) that can hold this information for a particular connection.

For example, for connection A – D I want to store :

node_A, 
node_D, 
crosssectional area (computed elsewhere) , 
regionB, 
regionB_thickness, 
regionB other properties, 
regionC, ....

The data can be double , int , string and could also be an array /vector etc.

1. First I considered creating structs or classes for regionB, regionC etc .
   But, for each connection A-D, certain properties like thickness of the region through which this connection passes are different.
   There will only be 3 or 4 different things I need to store pertaining to a region.
   Which data structure should I consider here (any STL container like vector?) Could you please suggest one? (would appreciate a code snippet)

2. To access a connection between nodes A-D, I want to make use of int node_A (an index).
   This probably means I need to use a hashmap or similar data structure.
   Can anyone please suggest a good data structure in C++ that can efficiently
   hold this sort of data for connection A -D described above? (would appreciate a code snippet)

thank you!

UPDATE
for some reasons, I can not make use of pkgs like boost. So want to know if I can use any libraries from STL

Answer 1

You should try to group stuff together when you can. You can group the information on each region together with something like the following:

class Region_Info {
  Region *ptr;
  int thickness;
  // Put other properties here.
};

Then, you can more easily create a data structure for your line segment, maybe something like the following:

class Line_Segment {
  int node_A;
  int node_D;
  int crosssectional_area;
  std::list<Region_Info>;
};

If you are limited to only 20 regions, then a list should work fine. A vector is also fine if you would prefer.