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gistfile1.txt

//  1. oldstring element is not in new  : abandon(delete)
//  2. new element is not in oldstring  : add(add)
func Difference(oldstring []string, newstring []string) map[string]string {
    var diff = make(map[string]string)
 
    // Loop two times, first to find oldstring strings not in newstring,
    // second loop to find newstring strings not in oldstring
    for i := 0; i < 2; i++ {
        for _, s1 := range oldstring {
            found := false
            for _, s2 := range newstring {
                if s1 == s2 {
                    found = true
                    break
                }   
            }   
            // String not found. We add it to return slice
            if !found && i == 0 { 
                diff[s1] = "delete"
            }   
            if !found && i != 0 { 
                diff[s1] = "add"
            }   
        }   
        // Swap the slices, only if it was the first loop
        if i == 0 { 
            oldstring, newstring = newstring, oldstring
        }   
    }   
    return diff
}