updated readme.md

Jatin86400 · web-flow · commit 1aeb5cee7fb7 · 2017-12-14T18:55:45.000+05:30
diff --git a/Competitive Coding/Tree/Binary Tree/preorder_traversal/readme.md b/Competitive Coding/Tree/Binary Tree/preorder_traversal/readme.md
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-readme
+# Preorder Traversal
+
+![alt text](https://javabeat.net/wp-content/uploads/2013/11/BST_Preorder.jpg)
+
+Algorithm Preorder(tree)
+   * Visit the root.
+   * Traverse the left subtree, i.e., call Preorder(left-subtree)
+   * Traverse the right subtree, i.e., call Preorder(right-subtree) 
