Data commit

Task/Cumulative-standard-deviation/C-sharp/cumulative-standard-deviation.cs

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+using System;
+using System.Collections.Generic;
+using System.Linq;
+
+namespace standardDeviation
+{
+    class Program
+    {
+        static void Main(string[] args)
+        {
+            List<double> nums = new List<double> { 2, 4, 4, 4, 5, 5, 7, 9 };
+            for (int i = 1; i <= nums.Count; i++)
+                Console.WriteLine(sdev(nums.GetRange(0, i)));
+        }
+
+        static double sdev(List<double> nums)
+        {
+            List<double> store = new List<double>();
+            foreach (double n in nums)
+                store.Add((n - nums.Average()) * (n - nums.Average()));
+
+            return Math.Sqrt(store.Sum() / store.Count);
+        }
+    }
+}