Given n sets of items. Each item has a value. The items in a set have similar values but vary by a small amount. The goal is to create new sets containing three items selected from the original sets such that the total of the values is within a given range. Only one item a source set can be selected.

For example: If we have the following starting sets:

• Set A - { 4.0, 3.8, 4.2 }
• Set B - { 7.0, 6.8, 7.2 }
• Set C - { 1.0, 0.9, 1.1 }
• Set D - { 6.5, 6.4, 6.6 }
• Set E - { 2.5, 2.4, 2.6 }

Goal is to create sets containing three elements such that the total is between 11.9 and 12.1.

• For example { 3.8, 7.2, 1.0 }
  

There can be unused elements.

Can someone suggest an algorithm for this problem?