Compare two slices of strings for equality in O(n) time.

slices.go

package slices

// Equal compares two slices of strings for equality in less than polynomial time worst case.
func Equal(s1, s2 []string) bool {
	if len(s1) != len(s2) {
		return false
	}

	o := make(map[string]int)
	for _, x := range s1 {
		o[x]++
	}

	for _, y := range s2 {
		o[y]--

		if o[y] == 0 {
			delete(o, y)
		}
	}

	return len(o) == 0
}