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Tree PostOrder Traversal
Binary Tree PostOrder Traversal
Introduction:
PostOrder traversal of a binary tree involves visiting the left subtree, the right subtree, and then the root node. It is used in various applications such as deleting the tree, postfix expression evaluation, etc.
class Node {
int data;
Node left, right;
Node(int item) {
data = item;
left = right = null;
}
}
void postOrder(Node node) {
if (node == null)
return;
postOrder(node.left);
postOrder(node.right);
System.out.print(node.data + " ");
}
Console Output:
4 5 2 3 1
N-ary Tree PostOrder Traversal
Introduction:
In an N-ary tree, each node can have more than two children. PostOrder traversal still follows the same principle: visit all children and then the node itself.
class NaryNode {
int data;
List children;
NaryNode(int data) {
this.data = data;
children = new ArrayList<>();
}
}
void postOrder(NaryNode node) {
if (node == null)
return;
for (NaryNode child : node.children) {
postOrder(child);
}
System.out.print(node.data + " ");
}
Console Output:
5 6 4 3 2 1
Threaded Binary Tree PostOrder Traversal
Introduction:
Threaded binary trees make use of pointers to the successor nodes, facilitating traversal without recursion or a stack. PostOrder traversal is slightly complex in threaded trees due to these pointers.
// Implementation specific to threaded trees
void postOrder(ThreadedNode root) {
// Custom logic to handle threaded nodes
}
Console Output:
Output specific to threaded tree structure
AVL Tree PostOrder Traversal
Introduction:
AVL trees are self-balancing binary search trees. PostOrder traversal remains the same as in a regular binary tree, but it considers the balanced nature of AVL trees.
void postOrder(AVLNode node) {
if (node == null)
return;
postOrder(node.left);
postOrder(node.right);
System.out.print(node.data + " ");
}
Console Output:
Output of balanced AVL tree
Expression Tree PostOrder Traversal
Introduction:
Expression trees represent expressions where leaves are operands and internal nodes are operators. PostOrder traversal is used to evaluate postfix expressions.
void postOrder(ExpressionNode node) {
if (node == null)
return;
postOrder(node.left);
postOrder(node.right);
System.out.print(node.value + " ");
}
Console Output:
a b + c d e + * *
