feat: calculator

homework/calculate/calculate.hpp

@@ -1,7 +1,34 @@
 #pragma once
 #include <string>
 
+auto add(const int lhs, const int rhs) -> std::string {
+    return std::to_string(lhs + rhs);
+}
+
+auto subtract(const int lhs, const int rhs) -> std::string {
+    return std::to_string(lhs - rhs);
+}
+
+auto multiply(const int lhs, const int rhs) -> std::string {
+    return std::to_string(lhs * rhs);
+}
+
+auto divide(const int lhs, const int rhs) -> std::string {
+    if (rhs != 0) {
+        return std::to_string(lhs / rhs);
+    }
+    return "Division by 0";
+}
+
 std::string calculate(const std::string& command, int first, int second) {
-    // TODO: Implement your solution here and return proper value
-    return "";
+    if (command == "add") {
+        return add(first, second);
+    } else if (command == "subtract") {
+        return subtract(first, second);
+    } else if (command == "multiply") {
+        return multiply(first, second);
+    } else if (command == "divide") {
+        return divide(first, second);
+    }
+    return "Invalid data";
 }