Add C# solutions

hellomrsun · hellomrsun · commit 8b8e04547b79 · 2020-10-17T19:46:05.000+02:00
diff --git a/October-LeetCoding-Challenge/17-Repeated-DNA-Sequences/Repeated-DNA-Sequences.cs b/October-LeetCoding-Challenge/17-Repeated-DNA-Sequences/Repeated-DNA-Sequences.cs
@@ -0,0 +1,14 @@
+public class Solution {
+    public IList<string> FindRepeatedDnaSequences(string s) {
+        if(s == null || s.Length == 0) return new List<string>();
+        var seen = new HashSet<string>();
+        var repeated = new HashSet<string>();
+        for(int i=0; i<s.Length-9; i++){
+            string curr = s.Substring(i, 10);
+            if(!seen.Add(curr)){
+                repeated.Add(curr);
+            }
+        }
+        return new List<string>(repeated);
+    }
+}
