Recall & Review
beginner
What is a Trie data structure?
A Trie is a tree-like data structure used to store a dynamic set of strings where keys are usually strings. Each node represents a character, and paths from root to leaves represent words.
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beginner
How does the search operation work in a Trie?
The search operation checks each character of the word in the Trie by moving from the root node through child nodes. If all characters are found and the last node marks the end of a word, the search returns true; otherwise, false.
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intermediate
What does it mean if a node's 'endOfWord' flag is false during a Trie search?
It means that although the prefix exists in the Trie, the exact word being searched for does not exist as a complete word in the Trie.
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intermediate
Why is Trie search efficient for prefix-based queries?
Trie search is efficient because it shares common prefixes among words, allowing quick traversal to the node representing the prefix without checking all words individually.
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intermediate
What is the time complexity of searching a word in a Trie?
The time complexity is O(m), where m is the length of the word being searched, because each character is checked once along the path.
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In a Trie search, what happens if a character is not found among the current node's children?
✗ Incorrect
If a character is missing in the current node's children, the word cannot be in the Trie, so the search returns false immediately.
What does the 'endOfWord' flag indicate in a Trie node?
✗ Incorrect
The 'endOfWord' flag shows that the path to this node forms a complete valid word stored in the Trie.
What is the main advantage of using a Trie for searching words?
✗ Incorrect
Trie allows fast prefix-based search by sharing common prefixes among words.
If you search for 'cat' in a Trie and find nodes for 'c' and 'a' but not 't', what is the result?
✗ Incorrect
Since 't' is missing, the word 'cat' does not exist in the Trie, so the search returns false.
What is the worst-case time complexity to search a word of length m in a Trie?
✗ Incorrect
The search checks each character once, so the time complexity is O(m).
Explain how the Trie search operation works step-by-step for the word 'dog'.
Think about moving through nodes for each letter and checking if the word ends there.
You got /6 concepts.
What is the role of the 'endOfWord' flag in Trie search, and why is it important?
Consider what happens if a prefix is found but the word is not complete.
You got /4 concepts.