Adding intPartitions object.

.idea/.name

@@ -0,0 +1 @@
+MainExercises.java

src/main/java/MainExercises.java

@@ -1,3 +1,5 @@
+import java.util.ArrayList;
+
 public class MainExercises
 {
     /*
@@ -19,10 +21,18 @@ 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][];
+        for(int i = 0; i < n; i++) {
+            triangle[i] = new char[i+1];
+            for(int j = 0; j <= i; j++){
+                if(j == 0 || i == n - 1 || i == j)
+                    triangle[i][j] = '*';
+                else
+                    triangle[i][j] = ' ';
+            }
+        }
 
-        // todo
-        return null;
-
+        return triangle;
     }
 
 
@@ -58,9 +68,37 @@ public class MainExercises
            - Number of columns: matrix[0].length (if rectangular)
    */
     public int[] spiralTraversal(int[][] matrix) {
-        // todo
-        return null;
+        int rows = matrix.length;
+        int cols = matrix[0].length;
+        int[] result = new int[rows * cols];
+        int index = 0;
+        int top = 0, bottom = rows - 1;
+        int left = 0, right = cols - 1;
+        while (top <= bottom && left <= right) {
+            for (int j = left; j <= right; j++) {
+                result[index++] = matrix[top][j];
             }
+            top++;
+            for (int i = top; i <= bottom; i++) {
+                result[index++] = matrix[i][right];
+            }
+            right--;
+            if (top <= bottom) {
+                for (int j = right; j >= left; j--) {
+                    result[index++] = matrix[bottom][j];
+                }
+                bottom--;
+            }
+            if (left <= right) {
+                for (int i = bottom; i >= top; i--) {
+                    result[index++] = matrix[i][left];
+                }
+                left++;
+            }
+        }
+        return result;
+    }
+
 
     /*
         integer partitioning is a combinatorics problem in discreet maths
@@ -89,15 +127,44 @@ public class MainExercises
         If you're familiar with Lists and ArrayLists, you can also edit the method's
         body to use them instead of arrays.
     */
-
+    private ArrayList<ArrayList<Integer>> intPartitionsHelper(int n, int biggest) {
+        ArrayList<ArrayList<Integer>> result = new ArrayList<>();
+        if (n == 0) {
+            result.add(new ArrayList<>());
+            return result;
+        }
+        for (int k = 1; k <= Math.min(biggest, n); k++) {
+            ArrayList<ArrayList<Integer>> subPartitions = intPartitionsHelper(n - k, k);
+            for (ArrayList<Integer> subPartition : subPartitions) {
+                ArrayList<Integer> newPartition = new ArrayList<>();
+                newPartition.add(k);
+                newPartition.addAll(subPartition);
+                result.add(newPartition);
+            }
+        }
+        return result;
+    }
     public int[][] intPartitions(int n) {
-        // todo
-        return null;
+        ArrayList<ArrayList<Integer>> answerList = intPartitionsHelper(n, n);
+        int[][] answerArray = new int[answerList.size()][];
+        for(int i = 0; i < answerList.size(); i++){
+            answerArray[(answerList.size() - i) - 1] = new int[answerList.get(i).size()];
+            for(int j = 0; j < answerList.get(i).size(); j++){
+                answerArray[(answerList.size() - i) - 1][j] = answerList.get(i).get(j);
+            }
+        }
+        return answerArray;
     }
 
 
-    public static void main()
+    public void main()
     {
-
+        int n = 4;
+        int[][] partitions = intPartitions(n);
+        for (int i = 0; i < partitions.length; i++) {
+            for(int j = 0; j < partitions[i].length; j++)
+                System.out.print(partitions[i][j]);
+            System.out.println();
+        }
     }
 }