Difference between sums of odd level and even level nodes of a Binary…

Tree/SumOfOddEvenLevelNodes.java

@@ -0,0 +1,80 @@
+import java.io.*; 
+import java.util.*; 
+// User defined node class 
+class Node { 
+      int data; 
+      Node left, right; 
+
+      // Constructor to create a new tree node 
+      Node(int key)  
+      { 
+           data  = key; 
+           left = right = null; 
+      } 
+} 
+class SumOfOddEvenLevelNodes { 
+      // return difference of  
+      // sums of odd level  and even level  
+      static int evenOddLevelDifference(Node root) 
+      { 
+             if (root == null) 
+                 return 0; 
+
+             // create a queue for  
+             // level order traversal 
+             Queue<Node> q = new LinkedList<>(); 
+             q.add(root); 
+
+             int level = 0;  
+             int evenSum = 0, oddSum = 0; 
+
+             // traverse until the  
+             // queue is empty 
+             while (q.size() != 0) { 
+                   int size = q.size(); 
+                   level++; 
+
+                   // traverse for complete level  
+                   while (size > 0) { 
+                          Node temp = q.remove(); 
+
+                          // check if level no.  
+                          // is even or odd and  
+                          // accordingly update  
+                          // the evenSum or oddSum  
+                          if (level % 2 == 0) 
+                              evenSum += temp.data; 
+                          else
+                              oddSum += temp.data; 
+
+                          // check for left child  
+                          if (temp.left != null) 
+                              q.add(temp.left); 
+
+                          // check for right child  
+                          if (temp.right != null) 
+                              q.add(temp.right); 
+                          size--; 
+                   } 
+             } 
+             return (oddSum - evenSum);   
+      } 
+
+      // Driver code 
+      public static void main(String args[]) 
+      { 
+             // construct a tree 
+             Node root = new Node(5); 
+             root.left = new Node(2); 
+             root.right = new Node(6); 
+             root.left.left = new Node(1); 
+             root.left.right = new Node(4); 
+             root.left.right.left = new Node(3); 
+             root.right.right = new Node(8); 
+             root.right.right.right = new Node(9); 
+             root.right.right.left = new Node(7); 
+
+             System.out.println("diffence between sums is " +  
+                                evenOddLevelDifference(root)); 
+      } 
+}