refactor: make not ugly

cmd/06/problem/problem.go

@@ -0,0 +1,37 @@
+// Package problem provides models and methods for representing a problem.
+package problem
+
+type Problem interface {
+	Solve() int
+}
+
+type problem struct {
+	operator string
+	operands []int
+}
+
+func From(operator string, operands []int) Problem {
+	return problem{
+		operator: operator,
+		operands: operands,
+	}
+}
+
+func (p problem) Solve() int {
+	result := 0
+
+	switch p.operator {
+	case "+":
+		for _, operand := range p.operands {
+			result += operand
+		}
+	case "*":
+		result = 1
+
+		for _, operand := range p.operands {
+			result *= operand
+		}
+	}
+
+	return result
+}