PostOrderBinaryTree.java

// Postorder Binary Tree
// Send Feedback
// For a given Binary Tree of integers, print the post-order traversal.
// ALTIMAGE

// The postorder traversal for the given binary tree will be 40 50 20 30 10
// Input Format:
// The first and the only line of input will contain the node data, all
// separated by a single space. Since -1 is used as an indication whether the
// left or right node data exist for root, it will not be a part of the node
// data.
// Output Format:
// The only line of output prints the post-order traversal of the given binary
// tree.
// Constraints:
// 1 <= N <= 10^6
// Where N is the total number of nodes in the binary tree.

// Time Limit: 1 sec
// Sample Input 1:
// 1 2 3 4 5 6 7 -1 -1 -1 -1 -1 -1 -1 -1
// Sample Output 1:
// 4 5 2 6 7 3 1
// Sample Input 2:
// 5 6 10 2 3 -1 -1 -1 -1 -1 9 -1 -1
// Sample Output 1:
// 2 9 3 6 10 5

// Following the structure used for Binary Tree

class BinaryTreeNode<T> {
    T data;
    BinaryTreeNode<T> left;
    BinaryTreeNode<T> right;

    public BinaryTreeNode(T data) {
        this.data = data;
        this.left = null;
        this.right = null;
    }
}

class Solution {

    public static void postOrder(BinaryTreeNode<Integer> root) {
        // Your code goes here
        if (root == null) {
            return;
        }
        postOrder(root.left);
        postOrder(root.right);
        System.out.print(root.data + " ");
    }

}