solves #114 in java

Author: anishLearnsToCode

README.md

@@ -107,7 +107,7 @@
 | 112  | [Path Sum](https://leetcode.com/problems/path-sum)                                                                                                        |                                           [![Java](assets/java.png)](src/PathSum.java) [![Python](assets/python.png)](python/path_sum.py)                                            |                                                                                                                                   |
 | 113  | [Path Sum II](https://leetcode.com/problems/path-sum-ii)                                                                                                  |                                                                    [![Java](assets/java.png)](src/PathSumII.java)                                                                    |                                                                                                                                   |
 | 114  | [Flatten Binary Tree to Linked List](https://leetcode.com/problems/flatten-binary-tree-to-linked-list)                                                    |                                                          [![Java](assets/java.png)](src/FlattenBinaryTreeToLinkedList.java)                                                          |                                                                                                                                   |
-| 116  | [Populating Next Right Pointers in Each Node](https://leetcode.com/problems/populating-next-right-pointers-in-each-node)                                  |                                                                                                                                                                                      |                                                                                                                                   |
+| 116  | [Populating Next Right Pointers in Each Node](https://leetcode.com/problems/populating-next-right-pointers-in-each-node)                                  |                                                      [![Java](assets/java.png)](src/PopulatingNextRightPointersInEachNode.java)                                                      |                                                                                                                                   |
 | 117  | [Populating Next Right Pointers in Each Node II](https://leetcode.com/problems/populating-next-right-pointers-in-each-node-ii)                            |                                                                                                                                                                                      |                                                                                                                                   |
 | 118  | [Pascal's Triangle](https://leetcode.com/problems/pascals-triangle)                                                                                       |                                   [![Java](assets/java.png)](src/PascalsTriangle.java) [![Python](assets/python.png)](python/pascals_triangle.py)                                    |                                                                                                                                   |
 | 119  | [Pascal's Triangle II](https://leetcode.com/problems/pascals-triangle-ii)                                                                                 |                                 [![Java](assets/java.png)](src/PascalsTriangleII.java) [![Python](assets/python.png)](python/pascals_triangle_ii.py)                                 |                                                                                                                                   |

src/HelloWorld.java

@@ -1,17 +1,17 @@
 public class HelloWorld {
     public static void main(String[] args) {
-        TreeNode root = new TreeNode(1);
-        root.left = new TreeNode(2);
-        root.right = new TreeNode(5);
-        root.left.left = new TreeNode(3);
-        root.left.right = new TreeNode(4);
-        root.right.right = new TreeNode(6);
+        PopulatingNextRightPointersInEachNode.Node root = new PopulatingNextRightPointersInEachNode.Node(1);
+        root.left = new PopulatingNextRightPointersInEachNode.Node(2);
+        root.right = new PopulatingNextRightPointersInEachNode.Node(3);
+        root.left.left = new PopulatingNextRightPointersInEachNode.Node(4);
+        root.left.right = new PopulatingNextRightPointersInEachNode.Node(5);
+        root.right.left = new PopulatingNextRightPointersInEachNode.Node(6);
+        root.right.right = new PopulatingNextRightPointersInEachNode.Node(7);
 
         TreePrinter.print(root);
 
-        FlattenBinaryTreeToLinkedList.flatten(root);
+        root = PopulatingNextRightPointersInEachNode.connect(root);
 
         TreePrinter.print(root);
-
     }
 }

src/MaximumDepthOfNAryTree.java

@@ -1,22 +1,22 @@
 import java.util.List;
 
-class Node {
-    public int val;
-    public List<Node> children;
+public class MaximumDepthOfNAryTree {
+    private static class Node {
+        public int val;
+        public List<Node> children;
 
-    public Node() {}
+        public Node() {}
 
-    public Node(int _val) {
-        val = _val;
-    }
+        public Node(int _val) {
+            val = _val;
+        }
 
-    public Node(int _val, List<Node> _children) {
-        val = _val;
-        children = _children;
+        public Node(int _val, List<Node> _children) {
+            val = _val;
+            children = _children;
+        }
     }
-};
 
-public class MaximumDepthOfNAryTree {
     public int maxDepth(Node root) {
         if (root == null) return 0;
         int maxDepth = 0;

src/NArayTreePreOrderTraversal.java

@@ -2,6 +2,22 @@
 import java.util.List;
 
 public class NArayTreePreOrderTraversal {
+    private static class Node {
+        public int val;
+        public List<Node> children;
+
+        public Node() {}
+
+        public Node(int _val) {
+            val = _val;
+        }
+
+        public Node(int _val, List<Node> _children) {
+            val = _val;
+            children = _children;
+        }
+    }
+
     List<Integer> result = new ArrayList<>();
 
     public List<Integer> preorder(Node root) {

src/NAryTreePostorderTraversal.java

@@ -2,6 +2,22 @@
 import java.util.List;
 
 public class NAryTreePostorderTraversal {
+    private static class Node {
+        public int val;
+        public List<Node> children;
+
+        public Node() {}
+
+        public Node(int _val) {
+            val = _val;
+        }
+
+        public Node(int _val, List<Node> _children) {
+            val = _val;
+            children = _children;
+        }
+    }
+
     List<Integer> result = new ArrayList<>();
 
     public List<Integer> postorder(Node root) {

src/PopulatingNextRightPointersInEachNode.java

@@ -0,0 +1,63 @@
+// https://leetcode.com/problems/populating-next-right-pointers-in-each-node
+// T: O(n)
+// S: O(n)
+
+import java.util.LinkedList;
+import java.util.Queue;
+
+public class PopulatingNextRightPointersInEachNode {
+    public static Node connect(Node root) {
+        if (root == null) return null;
+
+        final Queue<Node> queue = new LinkedList<>();
+        queue.add(root);
+        queue.add(null);
+        Node previous = null;
+
+        while (!queue.isEmpty()) {
+            final Node current = queue.poll();
+            if (current == null) {
+                previous = null;
+                if (!queue.isEmpty()) queue.add(null);
+                continue;
+            }
+
+            if (previous != null) previous.next = current;
+            previous = current;
+            addChildrenToQueue(queue, current);
+        }
+
+        return root;
+    }
+
+    private static void addChildrenToQueue(Queue<Node> queue, Node root) {
+        if (root.left != null) queue.add(root.left);
+        if (root.right != null) queue.add(root.right);
+    }
+
+    public static class Node implements TreePrinter.PrintableNode {
+        public int val;
+        public Node left;
+        public Node right;
+        public Node next;
+
+        public Node(int val) {
+            this.val = val;
+        }
+
+        @Override
+        public TreePrinter.PrintableNode getLeft() {
+            return left;
+        }
+
+        @Override
+        public TreePrinter.PrintableNode getRight() {
+            return right;
+        }
+
+        @Override
+        public String getText() {
+            return val + "";
+        }
+    }
+}