implement generateTriangle function in MainExercises

src/main/java/MainExercises.java

@@ -19,10 +19,19 @@ public class MainExercises
     the output has to be a two-dimensional array of characters, so don't just print the triangle!
  */
     public char[][] generateTriangle(int n) {
-
+        char[][] triangle = new char[n][];
-        // todo
+        for (int i = 0; i < n; i++) {
-        return null;
+            triangle[i] = new char[ i+1 ];
-
+            for (int j = 0; j <= i; j++) {
+                if(j == 0 || j == i || i == n - 1) {
+                    triangle[i][j] = '*';
+                }
+                else {
+                    triangle[i][j] = ' ';
+                }
+            }
+        }
+        return triangle;
     }