I have a slice A and another slice B. Slice A contains n elements and
slice B is a subset of slice A where each element is a pointer to
Slice A.
What would be the cheapest method to remove all elements from A which
is referred in B.
A and B may have duplicates and may not be sorted.
For example, growth rate O(n),
package main
import "fmt"
func remove(a []int, b []*int) []int {
d := make(map[*int]bool, len(b))
for _, e := range b {
d[e] = true
}
var c []int
if len(a) >= len(d) {
c = make([]int, 0, len(a)-len(d))
}
for i := range a {
if !d[&a[i]] {
c = append(c, a[i])
}
}
return c
}
func main() {
a := []int{0, 1, 2, 3, 4, 5, 6, 7}
fmt.Println(a)
b := []*int{&a[1], &a[3], &a[3], &a[7], &a[4]}
a = remove(a, b)
fmt.Println(a)
}
Playground: https://play.golang.org/p/-RpkH51FSt2
Output:
[0 1 2 3 4 5 6 7]
[0 2 5 6]