problems(cpp): add “1603. Design Parking System”

Signed-off-by: Matej Focko <mfocko@redhat.com>

problems/design-parking-system.cpp

@@ -0,0 +1,46 @@
+#include <cassert>
+
+class ParkingSystem {
+    int big;
+    int medium;
+    int small;
+
+    int& get(int carType)
+    {
+        switch (carType) {
+        case 1:
+            return big;
+        case 2:
+            return medium;
+        case 3:
+            return small;
+        default:
+            assert(false);
+        }
+    }
+
+public:
+    ParkingSystem(int big, int medium, int small)
+        : big(big)
+        , medium(medium)
+        , small(small)
+    {
+    }
+
+    bool addCar(int carType)
+    {
+        auto& space = get(carType);
+        if (space <= 0) {
+            return false;
+        }
+
+        --space;
+        return true;
+    }
+};
+
+/**
+ * Your ParkingSystem object will be instantiated and called as such:
+ * ParkingSystem* obj = new ParkingSystem(big, medium, small);
+ * bool param_1 = obj->addCar(carType);
+ */