do first question(triangel)

.idea/vcs.xml

@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <project version="4">
   <component name="VcsDirectoryMappings">
-    <mapping directory="$PROJECT_DIR$" vcs="Git" />
+    <mapping directory="" vcs="Git" />
   </component>
 </project>

src/main/java/MainExercises.java

@@ -20,8 +20,21 @@ public class MainExercises
  */
     public char[][] generateTriangle(int n) {
 
-        // todo
+        char[][] triangle =  new char[n][];
-        return null;
+
+        for(int i = 0 ; i < n ; i++){
+            triangle[i] = new char[i+1];
+            for(int j = 0 ; j < i+1 ; j++){
+                if(i == 0 || j == 0 || i== j || i == n-1 ){
+                    triangle[i][j] = '*';
+                }
+                else{
+                    triangle[i][j] = ' ';
+                }
+            }
+        }
+
+        return triangle;
 
     }
 
@@ -57,8 +70,9 @@ public class MainExercises
            - Number of rows:    matrix.length
            - Number of columns: matrix[0].length (if rectangular)
    */
+
     public int[] spiralTraversal(int[][] matrix) {
-        // todo
+
         return null;
     }