Trie Node Design and Initialization in DSA C++ - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a Trie node and what does it typically store?

A Trie node is a building block of a Trie data structure. It typically stores an array or map of child nodes for each possible character and a boolean flag to mark if the node represents the end of a word.

beginner

How do you initialize a Trie node in C++?

You create a class with a constructor that initializes all child pointers to nullptr and sets the end-of-word flag to false.

beginner

Why do we set all child pointers to nullptr during Trie node initialization?

Setting child pointers to nullptr means no children exist yet. It helps to check if a path exists when inserting or searching words.

beginner

What does the 'end of word' flag in a Trie node represent?

It marks that the path from the root to this node forms a complete word stored in the Trie.

beginner

In a Trie node design, how many children pointers are typically used for English lowercase letters?

Usually 26 pointers, one for each lowercase English letter from 'a' to 'z'.

What is the initial value of child pointers in a newly created Trie node?

A nullptr

B Random memory address

C Zero

D True

Child pointers are set to nullptr to indicate no children exist yet.

What does the boolean flag in a Trie node usually indicate?

A If the node has children

B If the node marks the end of a word

C If the node is the root

D If the node is empty

The boolean flag marks if the node represents the end of a stored word.

How many child pointers does a Trie node for lowercase English letters usually have?

A 128

B 10

C 52

D 26

There are 26 lowercase English letters, so 26 child pointers are used.

Which of these is the best data type for child pointers in a Trie node in C++?

A TrieNode*

B char

C bool

D int

Child pointers should be pointers to TrieNode objects.

Why do we need to initialize the 'end of word' flag to false in a Trie node?

A To mark the node as empty

B To save memory

C To indicate the node is not yet the end of a word

D To speed up insertion

Initially, the node does not represent the end of any word, so the flag is false.

Describe how you would design and initialize a Trie node in C++ for storing lowercase English words.

Think about what each node needs to store and how to prepare it for use.

Explain why initializing child pointers to nullptr and the end-of-word flag to false is important in a Trie node.

Consider what happens if these are not initialized properly.