GATE-CS-2009 Question 25

This question is a programming question from the GATE-CS-2009 examination. The question focuses on the implementation of a program for processing a binary tree data structure.

Problem Statement

The program is provided with a binary tree data structure where each node has a label and a list of children. The program must implement a function that selects all nodes in the tree which have at least one child with a label that matches a given input string.

The function should take two inputs:

1. A pointer to the root node of the binary tree.
2. A string input containing the label to match.

The function should return a list of nodes that have at least one child with a matching label.

Required Solution

The solution to this problem involves traversing the entire binary tree structure starting from the root node. For each node, we check if any of its children contain a matching label. If a match is found, we add the current node to the list of selected nodes.

The following is the pseudocode for the required solution:

def select_nodes(root, label):
    selected_nodes = []

    # Recursive function to traverse the binary tree
    def traverse(node):
        # Check if any child node has matching label
        for child in node.children:
            if child.label == label:
                selected_nodes.append(node)
                break
        
        # Recurse on all children
        for child in node.children:
            traverse(child)

    # Call the recursive function on the root node
    traverse(root)
    
    return selected_nodes

This solution makes use of a recursive function traverse which traverses all nodes in the binary tree. If any child node has a matching label, we add the parent node to the list of selected nodes. Finally, the function returns the list of selected nodes.

Conclusion

The solution to this problem involves traversing a binary tree and selecting nodes that have at least one matching child node. The provided pseudocode uses a recursive function to implement the traversal and maintains a list of selected nodes. This program can be easily implemented in any programming language that supports recursion and data structures.