Arrange pairs of numbers so that members of adjacent pairs are equal

Question

I would like to arrange the following items, forming the longest chain possible starting with 12-8 and matching the numbers end to end.

My items are 7-4, 11-8, 11-11

Answer 1

you need recursion, but it might not work on a bigger data set: something like this.

DISCLAIMER: This is probably not the most optimized solution (complexity O(N!)) but it is very simple to implement if you are allowed to use recursion

(this is not objective-c code, it's an algorithm, translate it yourself, sorry i don't know objective-c)

list function sortTupleList(list a, list b) //b is the current list
  list biggest = newlist()
  int target = b.last()[1]
  for(tuple k in a)
    if (k[0] == target)
      list n = sortTupleList(a.remove(k), b.add(k))
      if(n.size > biggest.size())
        biggest = n
      end if
    end if
  end for
  if (biggest == emptylist)
    return b
  else
    return biggest
end function


list function caller(list a)
  list b = newlist()
  b.add(12-8)
  a.remove(12-8)
  return sortTupleList(a,b)
end function

This function will test every single pattern starting from 12-8 and compare their size