add Binary Tree traversal DFS Algorithm

Author: inamcodes

src/main/java/com/thealgorithms/tree/Binary Tree/DFS.Java

@@ -0,0 +1,53 @@
+package com.thealgorithms.tree.BinaryTree;
+
+public class DFS {
+
+    // Inorder
+    void inorder(Node node) {
+        if (node == null) return;
+        inorder(node.left);
+        System.out.print(node.val + " ");
+        inorder(node.right);
+    }
+
+    // Preorder
+    void preorder(Node node) {
+        if (node == null) return;
+        System.out.print(node.val + " ");
+        preorder(node.left);
+        preorder(node.right);
+    }
+
+    // Postorder
+    void postorder(Node node) {
+        if (node == null) return;
+        postorder(node.left);
+        postorder(node.right);
+        System.out.print(node.val + " ");
+    }
+
+    public static void main(String[] args) {
+        BinaryTreeDFS tree = new BinaryTreeDFS();
+
+        Node root = new Node(4);
+        root.left       = new Node(2);
+        root.right      = new Node(6);
+        root.left.left  = new Node(1);
+        root.left.right = new Node(3);
+        root.right.left = new Node(5);
+        root.right.right= new Node(7);
+
+        System.out.print("Inorder:   "); tree.inorder(root);   // 1 2 3 4 5 6 7
+        System.out.print("\nPreorder:  "); tree.preorder(root);  // 4 2 1 3 6 5 7
+        System.out.print("\nPostorder: "); tree.postorder(root); // 1 3 2 5 7 6 4
+    }
+}
+
+class Node {
+    int val;
+    Node left, right;
+
+    Node(int val) {
+        this.val = val;
+    }
+}