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 nodes represent words or prefixes.
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intermediate
How does a Trie help in finding the longest word in a dictionary?
A Trie allows efficient prefix checking. By building a Trie from dictionary words, we can traverse nodes only if the prefix is a valid word, helping find the longest word where all prefixes exist.
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intermediate
What is the main condition to continue traversing in the Trie when searching for the longest word?
We only continue traversing to child nodes if the current node marks the end of a valid word, ensuring all prefixes of the candidate word exist in the dictionary.
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intermediate
Why do we prefer DFS (Depth-First Search) over BFS (Breadth-First Search) in finding the longest word in a Trie?
DFS explores deeper paths first, which helps find longer words by going down the Trie branches fully. BFS finds shorter words first, which is less efficient for this problem.
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beginner
What is the time complexity of building a Trie from n words with average length m?
The time complexity is O(n * m) because each word of length m is inserted character by character into the Trie.
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What does each node in a Trie represent?
✗ Incorrect
Each node in a Trie represents a single character of a word.
When searching for the longest word in a Trie, you should only continue if:
✗ Incorrect
We continue only if the current node marks the end of a valid word to ensure all prefixes exist.
Which traversal method is best to find the longest word in a Trie?
✗ Incorrect
DFS explores deeper paths first, helping find the longest word.
What is the main advantage of using a Trie for prefix-based problems?
✗ Incorrect
Trie allows efficient checking if a prefix exists in the dictionary.
If you have 1000 words each of length 10, what is the approximate time to build a Trie?
✗ Incorrect
Building a Trie takes O(n * m), here 1000 * 10 = 10,000 operations.
Explain how a Trie is used to find the longest word in a dictionary where every prefix is also a word.
Think about checking prefixes and exploring deep paths.
You got /4 concepts.
Describe the steps to build a Trie and then find the longest word with all prefixes present.
Focus on insertion and traversal conditions.
You got /5 concepts.