added exo

Algorithms/TriangleExercice.cs

@@ -0,0 +1,34 @@
+namespace Algorithms;
+
+using System;
+using System.Numerics;
+using System.Xml.Serialization;
+
+public class TriangleExercice
+{
+    public static string Repeat(string s, int n)
+    {
+        string ret = "";
+        for (int i = 0; i < n; i++)
+        {
+            ret = ret + s;
+        }
+        return ret;
+    }
+
+    public static string BuildTriangle(int height)
+    {
+        string ret = "";
+        for (int i = 0; i < height; i++)
+        {
+            int nbrStarts = 2 * i + 1;
+            int nbrSpaces = height - (i + 1);
+            string spaces = Repeat("_", nbrSpaces);
+            string starts = Repeat("*", nbrStarts);
+            ret += "" + spaces + starts + "\n";
+
+        }
+        return ret;
+    }
+
+}