Java Exercises: Get the preorder traversal of its nodes' values of a given a binary tree.
Java Basic: Exercise-125 with Solution
Write a Java program to get the preorder traversal of its nodes' values of a given a binary tree.
Example:
Expected output: 10 20 40 50 30
Sample Binary Tree

Preorder Traversal:

Sample Solution:
Java Code:
class Node
{
int key;
Node left, right;
public Node(int item)
{
key = item;
left = right = null;
}
}
class BinaryTree
{
// Root of Binary Tree
Node root;
BinaryTree()
{
root = null;
}
// Print the nodes of binary tree
void print_Preorder(Node node)
{
if (node == null)
return;
/* Print data of node */
System.out.print(node.key + " ");
print_Preorder(node.left);
print_Preorder(node.right);
}
void print_Preorder()
{
print_Preorder(root);
}
// Driver method
public static void main(String[] args)
{
BinaryTree tree = new BinaryTree();
tree.root = new Node(55);
tree.root.left = new Node(21);
tree.root.right = new Node(80);
tree.root.left.left = new Node(9);
tree.root.left.right = new Node(29);
tree.root.right.left = new Node(76);
tree.root.right.right = new Node(91);
System.out.println("Preorder traversal of binary tree is: ");
tree.print_Preorder();
}
}
Sample Output:
Preorder traversal of binary tree is: 55 21 9 29 80 76 91
Flowchart:

Java Code Editor:
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Previous: Write a Java program to find the index of a value in a sorted array. If the value does not find return the index where it would be if it were inserted in order.
Next: Write a Java program to get the inorder traversal of its nodes' values of a given a binary tree.
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Java: Tips of the Day
getEnumMap
Converts to enum to Map where key is the name and value is Enum itself.
public static <E extends Enum<E>> Map<String, E> getEnumMap(final Class<E> enumClass) { return Arrays.stream(enumClass.getEnumConstants()) .collect(Collectors.toMap(Enum::name, Function.identity())); }
Ref: https://bit.ly/3xXcFZt
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