feat: add cs solution to lc problem: No.2391 (#1990)

Author: dev-mauli

solution/2300-2399/2391.Minimum Amount of Time to Collect Garbage/README.md

@@ -365,6 +365,27 @@ impl Solution {
 }
 ```
 
+### **C#**
+
+```cs
+public class Solution {
+    public int GarbageCollection(string[] garbage, int[] travel) {
+        int len = garbage.Length;
+        int res = 0;
+        HashSet<char> s = new HashSet<char>();
+        for (int i = len - 1; i >= 0; i--) {
+            foreach (char ch in garbage[i].ToCharArray()) {
+                if (!s.Contains(ch))
+                    s.Add(ch);
+            }
+            res += garbage[i].Length;
+            res += i > 0 ? s.Count * travel[i - 1] : 0;
+        }
+        return res;
+    }
+}
+```
+
 ### **...**
 
 ```

solution/2300-2399/2391.Minimum Amount of Time to Collect Garbage/README_EN.md

@@ -346,6 +346,27 @@ impl Solution {
 }
 ```
 
+### **C#**
+
+```cs
+public class Solution {
+    public int GarbageCollection(string[] garbage, int[] travel) {
+        int len = garbage.Length;
+        int res = 0;
+        HashSet<char> s = new HashSet<char>();
+        for (int i = len - 1; i >= 0; i--) {
+            foreach (char ch in garbage[i].ToCharArray()) {
+                if (!s.Contains(ch))
+                    s.Add(ch);
+            }
+            res += garbage[i].Length;
+            res += i > 0 ? s.Count * travel[i - 1] : 0;
+        }
+        return res;
+    }
+}
+```
+
 ### **...**
 
 ```

solution/2300-2399/2391.Minimum Amount of Time to Collect Garbage/Solution.cs

@@ -0,0 +1,16 @@
+public class Solution {
+    public int GarbageCollection(string[] garbage, int[] travel) {
+        int len = garbage.Length;
+        int res = 0;
+        HashSet<char> s = new HashSet<char>();
+        for (int i = len - 1; i >= 0; i--) {
+            foreach (char ch in garbage[i].ToCharArray()) {
+                if (!s.Contains(ch))
+                    s.Add(ch);
+            }
+            res += garbage[i].Length;
+            res += i > 0 ? s.Count * travel[i - 1] : 0;
+        }
+        return res;
+    }
+}