cleanup

WebApp/Helper.cs

@@ -14,4 +14,23 @@ public static class Helper
         }
         return result;
     }
+
+    public static (int Row, int Col) ToRowCol(string letters)
+    {
+        int row = 0;
+        int col = 0;
+        foreach (var item in letters)
+        {
+            if (item >= 'A')
+            {
+                row = row * 26 + (item - 'A' + 1);
+            }
+            else if (item >= '0')
+            {
+                col = col * 10 + (item - '0');
+            }
+        }
+
+        return (row, col);
+    }
 }