Add union, intersection, difference, subset to ZSet

Signed-off-by: Devansh Singh <[email protected]>

set/set.go

@@ -60,7 +60,6 @@ func (s *Set) Remove(element string) error {
 
 func (s1 *Set) Union(s2 Set) Set {
 	elements := NewSet()
-
 	for element := range s1.Elements {
 		elements.Add(element)
 	}

zset/zset.go

@@ -59,3 +59,43 @@ func (z *ZSet) Members() []string {
 
 	return z.Elements.members()
 }
+
+func (z1 *ZSet) Union(z2 ZSet) ZSet {
+	elements := NewZSet()
+	for _, element := range z1.Members() {
+		elements.Add(element)
+	}
+	for _, element := range z2.Members() {
+		elements.Add(element)
+	}
+	return elements
+}
+
+func (z1 *ZSet) Intersection(z2 ZSet) ZSet {
+	elements := NewZSet()
+	for _, element := range z1.Members() {
+		if z2.Exists(element) {
+			elements.Add(element)
+		}
+	}
+	return elements
+}
+
+func (z1 *ZSet) Difference(z2 ZSet) ZSet {
+	elements := NewZSet()
+	for _, element := range z1.Members() {
+		if !z2.Exists(element) {
+			elements.Add(element)
+		}
+	}
+	return elements
+}
+
+func (z1 *ZSet) Subset(z2 ZSet) bool {
+	for _, element := range z1.Members() {
+		if !z2.Exists(element) {
+			return false
+		}
+	}
+	return true
+}