feat: add C# solution to lc problem: No.1603 (doocs#1661)

No.1603.Design Parking System

Author: bbtzza

solution/1600-1699/1603.Design Parking System/README.md

@@ -257,6 +257,33 @@ void parkingSystemFree(ParkingSystem* obj) {
 */
 ```
 
+### **C#**
+
+```cs
+public class ParkingSystem {
+
+    private List<int> cnt;
+    
+    public ParkingSystem(int big, int medium, int small) {
+        cnt = new List<int>() {0 , big, medium, small};
+    }
+    
+    public bool AddCar(int carType) {
+        if (cnt[carType] == 0) {
+            return false;
+        }
+        --cnt[carType];
+        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);
+ */
+```
+
 ### **...**
 
 ```

solution/1600-1699/1603.Design Parking System/README_EN.md

@@ -241,6 +241,34 @@ void parkingSystemFree(ParkingSystem* obj) {
 */
 ```
 
+### **C#**
+
+```cs
+public class ParkingSystem {
+
+    private List<int> cnt;
+    
+    public ParkingSystem(int big, int medium, int small) {
+        cnt = new List<int>() {0 , big, medium, small};
+    }
+    
+    public bool AddCar(int carType) {
+        if (cnt[carType] == 0) {
+            return false;
+        }
+        --cnt[carType];
+        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);
+ */
+```
+
+
 ### **...**
 
 ```

solution/1600-1699/1603.Design Parking System/Solution.cs

@@ -0,0 +1,22 @@
+public class ParkingSystem {
+
+    private List<int> cnt;
+    
+    public ParkingSystem(int big, int medium, int small) {
+        cnt = new List<int>() {0 , big, medium, small};
+    }
+    
+    public bool AddCar(int carType) {
+        if (cnt[carType] == 0) {
+            return false;
+        }
+        --cnt[carType];
+        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);
+ */