TreeNode notes

src/Traversal.java

@@ -1,5 +1,84 @@
 public class Traversal {
   public static void main(String[] args) {
+    TreeNode root = new TreeNode(10);
 
+    root.left = new TreeNode(9);
+    root.right = new TreeNode(15);
+
+    root.left.left = new TreeNode(5);
+    root.left.right = new TreeNode(2);
+
+    root.right = new TreeNode(15);
+    root.right.left = new TreeNode(-3);
+    root.right.right = new TreeNode(5);
+
+    root.right.right.right = new TreeNode(22);
+
+    // preorder(root);
+
+    //print out the sum
+    // int result = sum(root);
+    // System.out.println(result);
+
+    //print out oddSum
+    int result = oddSum(root);
+    System.out.println(result);
+
+
+  }
+
+    //methode to calculate the sum of the node odd in the tree, this methode return value so it's an integer method return an int.
+  public static int oddSum(TreeNode node){
+    if(node == null){
+      return 0;
+    }
+    int total = 0;
+    if(node.data % 2 != 0){
+      total += node.data;
+
+    }
+    total += oddSum(node.left);
+    total += oddSum(node.right);
+
+    return total;
+  }
+
+
+  //ordering the nodes and print them up
+  public static void preorder(TreeNode current){ //void because we don't print anything
+    //if null: return
+    if(current == null) return; //current is the TreeNode.  
+
+    //print data
+    System.out.println(current.data); //current.data is to print the data inside current.
+
+    //search left
+    preorder(current.left); 
+
+    //search right
+    preorder(current.right);
+
+  }
+
+
+  //methode to calculate the oddSum of the node odd in the tree, this methode return value so it's an integer method return an int.
+  public static int sum(TreeNode node){
+    //if null == 0
+    //because the method return a value, we need to return something. here if null, return 0.
+    if (node == null) return 0;
+    //else myValue + sum of left subtree + sum of right subtree
+
+    //initialisation of total at root data
+    int total = node.data;
+
+    //add sum of left subtree to my total. 
+    //we use the method that we are in RN, because it's a method that does the sum of the treeNode
+    total += sum(node.left);
+
+    //add sum of right subtree to my total.
+    total += sum(node.right);
+
+    //return total
+    return total;
   }
 }

src/TreeNode.java

@@ -1,4 +1,10 @@
 public class TreeNode {
+    public int data;
+    public TreeNode left;
+    public TreeNode right;
+
+    public TreeNode(int data){
+        this.data = data;
+    }
 
-
 }