﻿ Java - Postorder traversal of its node of a binary tree

# Java: Get the Postorder traversal of its nodes' values of a given a binary tree

## Java Basic: Exercise-127 with Solution

Write a Java program to get the Postorder traversal of its nodes' values in a binary tree.

Sample Binary Tree

Postorder 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_Postorder(Node node)
{
if (node == null)
return;

print_Postorder(node.left);

print_Postorder(node.right);

System.out.print(node.key + " ");
}

// Wrappers over above recursive functions
void print_Postorder()
{
print_Postorder(root);
}
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("\nPostorder traversal of binary tree is: ");
tree.print_Postorder();
}
}
```
```

Sample Output:

```Postorder traversal of binary tree is:
9 29 21 76 91 80 55
```

Flowchart:

Java Code Editor:

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## Java: Tips of the Day

DropElements

Removes elements in an array until the passed function returns true. Returns the remaining elements in the array.

Loop through the array, using Arrays.copyOfRange() to drop the first element of the array until the returned value from the function is true. Returns the remaining elements.

```public static int[] dropElements(int[] elements, IntPredicate condition) {
while (elements.length > 0 && !condition.test(elements[0])) {
elements = Arrays.copyOfRange(elements, 1, elements.length);
}
return elements;
}
```

Ref: https://bit.ly/37YWqzD

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