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Question

I have a function that is somewhat similar to the traveling salesman problem that I am trying to make recursive. I think it is working but I am having some trouble getting the appending to work correctly on large datasets. Here is what I have...main should be written to be recursive so I can call a variable number of recursions...https://play.golang.org/p/Lz8arHybFr

package main

type Foo struct {
    StartPoint string
    EndPoint string 
    distance int
}

func (f *Foo) Connects(endFoo *Foo) bool {
    return f.EndPoint == endFoo.StartPoint
}

func (f *Foo) Completes(endFoo *Foo) bool {
    return f.StartPoint == endFoo.EndPoint
}

var fl = []*Foo{
    // many foo in here
}

func main() {

    completeList := [][]*Foo{}

    for _, first := range fl {
        for _, second := range fl {
            if second.Connects(first) {
                if second.Completes(first) {
                    l := []*Foo{
                        first, second,
                    }
                    completeList = append(completeList, l)
                }

                //if the connection is made, but not complete, keep going
                for _, third := range fl {
                    if third.Connects(second) {
                        if first.Completes(third) {
                            l := []*Foo{
                                first, second, third,
                            }
                            completeList = append(completeList, l)
                        }
                    }
                }
            }
        }
    }

}

Answer 1

I came up with 2 recursions, please, check it on your data: (I suppose you're going to make this parallel, so this will be easier with 2 recursions, just as a go rec2(...))

func main() {
    rec(0,0)
}

func rec(a, b int) {
    if a >= len(fl) || b >= len(fl) || a == b {
        return
    }
    aa, bb := fl[a], fl[b]
    if !aa.Connects(bb) {
        rec(a, b+1)
        return
    }
    l := []*Foo{
        aa, bb,
    }
    completeList = append(completeList, l)

    rec2(0, a, b)
}

func rec2(c, a, b int) {
    if c >= len(fl) || a == c || b == c {
        return
    }
    cc, aa, bb := fl[c], fl[a], fl[b]
    if cc.Connects(bb) && aa.Completes(cc) {
         l := []*Foo{
              aa, bb, cc,
         }
         completeList = append(completeList, l)
    }
    rec2(c+1, a, b)
}