diff --git a/random_weighted.go b/random_weighted.go
index 61ee717..d5802a8 100644
--- a/random_weighted.go
+++ b/random_weighted.go
@@ -62,6 +62,8 @@ func (rw *RandW) All() map[interface{}]int {
 func (rw *RandW) RemoveAll() {
 	rw.items = make([]*randWeighted, 0)
 	rw.r = rand.New(rand.NewSource(time.Now().Unix()))
+	rw.sumOfWeights = 0
+	rw.n = 0
 }
 
 // Reset resets the balancing algorithm.
diff --git a/random_weighted_test.go b/random_weighted_test.go
index 5b4d51a..d161b08 100644
--- a/random_weighted_test.go
+++ b/random_weighted_test.go
@@ -31,6 +31,19 @@ func TestRandW_Next(t *testing.T) {
 		t.Error("the algorithm is wrong", results)
 	}
 
+	all := w.All()
+	countOK := 0
+	for index := range all {
+		if (index == "server1" && all[index] == 5) ||
+			(index == "server2" && all[index] == 2) ||
+			(index == "server3" && all[index] == 3) {
+			countOK++
+		}
+	}
+	if countOK != 3 {
+		t.Error("the algorithm is wrong")
+	}
+
 	w.RemoveAll()
 	w.Add("server1", 7)
 	w.Add("server2", 9)
@@ -48,6 +61,17 @@ func TestRandW_Next(t *testing.T) {
 	// }
 
 	t.Log("the results: ", results)
+
+	w.RemoveAll()
+	next := w.Next()
+	if next != nil {
+		t.Error("the algorithm is wrong")
+	}
+	w.Add("server1", 3)
+	next = w.Next()
+	if next == nil {
+		t.Error("the algorithm is wrong")
+	}
 }
 
 func checkResults(v, min, max int) bool {
diff --git a/roundrobin_weighted.go b/roundrobin_weighted.go
index 4213acf..498658c 100644
--- a/roundrobin_weighted.go
+++ b/roundrobin_weighted.go
@@ -93,14 +93,8 @@ func (w *RRW) Next() interface{} {
 }
 
 func gcd(x, y int) int {
-	var t int
-	for {
-		t = (x % y)
-		if t > 0 {
-			x = y
-			y = t
-		} else {
-			return y
-		}
+	for y != 0 {
+		x, y = y, x%y
 	}
+	return x
 }
diff --git a/roundrobin_weighted_test.go b/roundrobin_weighted_test.go
index 0f156f4..cecc952 100644
--- a/roundrobin_weighted_test.go
+++ b/roundrobin_weighted_test.go
@@ -31,6 +31,19 @@ func TestRRW_Next(t *testing.T) {
 		t.Error("the algorithm is wrong", results)
 	}
 
+	all := w.All()
+	countOK := 0
+	for index := range all {
+		if (index == "server1" && all[index] == 5) ||
+			(index == "server2" && all[index] == 2) ||
+			(index == "server3" && all[index] == 3) {
+			countOK++
+		}
+	}
+	if countOK != 3 {
+		t.Error("the algorithm is wrong")
+	}
+
 	w.RemoveAll()
 	w.Add("server1", 7)
 	w.Add("server2", 9)
@@ -46,4 +59,35 @@ func TestRRW_Next(t *testing.T) {
 	if results["server1"] != 7000 || results["server2"] != 9000 || results["server3"] != 13000 {
 		t.Error("the algorithm is wrong", results)
 	}
+
+	w.RemoveAll()
+	next := w.Next()
+	if next != nil {
+		t.Error("the algorithm is wrong")
+	}
+	w.Add("server1", 3)
+	next = w.Next()
+	if next == nil {
+		t.Error("the algorithm is wrong")
+	}
+}
+
+func TestGCB(t *testing.T) {
+	tests := []struct {
+		name string
+		args [2]int
+		want int
+	}{
+		{"0,0", [2]int{0, 0}, 0},
+		{"1997,615", [2]int{1997, 6150}, 1},
+		{"481,221", [2]int{481, 221}, 13},
+		{"12,18", [2]int{12, 18}, 6},
+	}
+	for _, tt := range tests {
+		n1 := tt.args[0]
+		n2 := tt.args[1]
+		if got := gcd(n1, n2); got != tt.want {
+			t.Errorf("gcb(%v, %v) = %v ; want = %v", n1, n2, got, tt.want)
+		}
+	}
 }
diff --git a/smooth_weighted.go b/smooth_weighted.go
index 0633c46..cbb8bcb 100644
--- a/smooth_weighted.go
+++ b/smooth_weighted.go
@@ -66,23 +66,14 @@ func (w *SW) All() map[interface{}]int {
 
 // Next returns next selected server.
 func (w *SW) Next() interface{} {
-	i := w.nextWeighted()
-	if i == nil {
+	switch w.n {
+	case 0:
 		return nil
+	case 1:
+		return w.items[0].Item
+	default:
+		return nextSmoothWeighted(w.items).Item
 	}
-	return i.Item
-}
-
-// nextWeighted returns next selected weighted object.
-func (w *SW) nextWeighted() *smoothWeighted {
-	if w.n == 0 {
-		return nil
-	}
-	if w.n == 1 {
-		return w.items[0]
-	}
-
-	return nextSmoothWeighted(w.items)
 }
 
 //https://github.com/phusion/nginx/commit/27e94984486058d73157038f7950a0a36ecc6e35
@@ -92,10 +83,6 @@ func nextSmoothWeighted(items []*smoothWeighted) (best *smoothWeighted) {
 	for i := 0; i < len(items); i++ {
 		w := items[i]
 
-		if w == nil {
-			continue
-		}
-
 		w.CurrentWeight += w.EffectiveWeight
 		total += w.EffectiveWeight
 		if w.EffectiveWeight < w.Weight {
diff --git a/smooth_weighted_test.go b/smooth_weighted_test.go
index ee288e8..2f9d2c0 100644
--- a/smooth_weighted_test.go
+++ b/smooth_weighted_test.go
@@ -31,6 +31,19 @@ func TestSW_Next(t *testing.T) {
 		t.Error("the algorithm is wrong")
 	}
 
+	all := w.All()
+	countOK := 0
+	for index := range all {
+		if (index == "server1" && all[index] == 5) ||
+			(index == "server2" && all[index] == 2) ||
+			(index == "server3" && all[index] == 3) {
+			countOK++
+		}
+	}
+	if countOK != 3 {
+		t.Error("the algorithm is wrong")
+	}
+
 	w.RemoveAll()
 	w.Add("server1", 7)
 	w.Add("server2", 9)
@@ -46,4 +59,15 @@ func TestSW_Next(t *testing.T) {
 	if results["server1"] != 7000 || results["server2"] != 9000 || results["server3"] != 13000 {
 		t.Error("the algorithm is wrong")
 	}
+
+	w.RemoveAll()
+	next := w.Next()
+	if next != nil {
+		t.Error("the algorithm is wrong")
+	}
+	w.Add("server1", 3)
+	next = w.Next()
+	if next == nil {
+		t.Error("the algorithm is wrong")
+	}
 }