Merge pull request 'Implement 3 methods; Triangle, Traversal and Partitions' (#1) from develop into main

Reviewed-on: saeedjamali/HW-02-git-and-java-practice-Saeed#1

src/main/java/MainExercises.java

@@ -1,3 +1,6 @@
+import java.util.ArrayList;
+import java.util.List;
+
 public class MainExercises
 {
     /*
@@ -19,9 +22,18 @@ 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) {
-
-        // todo
-        return null;
+        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 (i == 0 || i == n - 1 || j == 0 || j == i) {
+                    triangle[i][j] = '*';
+                } else {
+                    triangle[i][j] = ' ';
+                }
+            }
+        }
+        return triangle;
 
     }
 
@@ -58,8 +70,47 @@ public class MainExercises
            - Number of columns: matrix[0].length (if rectangular)
    */
     public int[] spiralTraversal(int[][] matrix) {
-        // todo
-        return null;
+        int[] result = new int[matrix.length * (matrix[0].length)];
+        int topI = 0;
+        int leftJ = 0;
+        int botI = matrix.length - 1;
+        int rightJ = matrix[0].length - 1;
+        int count = 0;
+        int turn = 1; // 1 for topI, 2 for rightJ, 3 for botI, 4 for leftJ
+        while (count < matrix.length * matrix[0].length) {
+            if (turn == 1) {
+                for(int j = leftJ; j <= rightJ; j++) {
+                    result[count] = matrix[topI][j];
+                    count++;
+                }
+                topI++;
+                turn = 2;
+            } else if (turn == 2) {
+                for (int i = topI; i <= botI; i++) {
+                    result[count] = matrix[i][rightJ];
+                    count++;
+                }
+                rightJ--;
+                turn = 3;
+            } else if (turn == 3) {
+                for (int j = rightJ; j >= leftJ; j--) {
+                    result[count] = matrix[botI][j];
+                    count++;
+                }
+                botI--;
+                turn = 4;
+            } else if (turn == 4) {
+                for (int i = botI; i >= topI; i--) {
+                    result[count] = matrix[i][leftJ];
+                    count++;
+                }
+                leftJ++;
+                turn = 1;
+            }
+
+
+        }
+        return result;
     }
 
     /*
@@ -84,15 +135,42 @@ public class MainExercises
         You should generate all partitions of the input number.
 
         Hint: You can determine the size and order of the arrays by finding the pattern
-        of partitions and their count. Trust me, this one's fun and easy :)
+        of partitions and their count. Trust me, this one's !fun and !easy :|
 
         If you're familiar with Lists and ArrayLists, you can also edit the method's
         body to use them instead of arrays.
     */
 
 public int[][] intPartitions(int n) {
-        // todo
-        return null;
+    List<List<Integer>> partitions = new ArrayList<>();
+    List<Integer> current = new ArrayList<>();
+    addPartition(n, n,current, partitions);
+
+    int[][] result = new int[partitions.size()][];
+    for (int i = 0; i < partitions.size(); i++) {
+        List<Integer> p = partitions.get(i);
+        int size = p.size();
+        result[i] = new int[size];
+        for (int j = 0; j < size;j++) {
+            result[i][j] =  p.get(j);
+        }
+    }
+    return result;
+}
+
+private void addPartition(int remaining, int maxAllowed,
+                          List<Integer> current, List<List<Integer>> partitions){
+    if (remaining == 0) {
+        partitions.add(new ArrayList<>(current));
+        return;
+    }
+
+    for (int j = Math.min(remaining, maxAllowed); j >=1; j--) {
+        current.add(j);
+        addPartition(remaining - j, j, current, partitions);
+        current.remove(current.size() - 1);
+    }
+
 }