Add strategy pattern

strategy.go

@@ -0,0 +1,39 @@
+package main
+
+import "fmt"
+
+type Operator interface {
+	Apply(int, int) int
+}
+
+type Operation struct {
+	Operator Operator
+}
+
+func (o *Operation) Operate(leftValue, rightValue int) int {
+	return o.Operator.Apply(leftValue, rightValue)
+}
+
+type Multiplication struct{}
+
+func (Multiplication) Apply(lval, rval int) int {
+	return lval * rval
+}
+
+type Addition struct{}
+
+func (Addition) Apply(lval, rval int) int {
+	return lval + rval
+}
+
+func main() {
+	mult := Operation{Multiplication{}}
+
+	// Outputs 15
+	fmt.Println(mult.Operate(3, 5))
+
+	pow := Operation{Addition{}}
+
+	// Outputs 8
+	fmt.Println(pow.Operate(3, 5))
+}