Bird
Raised Fist0

Which approach guarantees an optimal solution for this problem?

easy🔍 Pattern Recognition Q11 of Q15
Subsets & Combinations - Number of Valid Words for Each Puzzle
You are given a list of words and a list of puzzles, each puzzle being a string of 7 unique letters. For each puzzle, you need to count how many words satisfy two conditions: the word contains the puzzle's first letter, and all letters of the word are contained within the puzzle. Which approach guarantees an optimal solution for this problem?
AUse bitmasking to represent words and puzzles, combined with a trie to efficiently count valid words for each puzzle.
BUse a brute force approach checking each word against each puzzle with set containment checks.
CUse a dynamic programming approach to count subsets of puzzle letters matching words.
DUse a greedy approach selecting words that share the most letters with puzzles.
Step-by-Step Solution

  1. Step 1: Understand problem constraints

    The problem requires checking subsets of puzzle letters and matching words efficiently, which is expensive with brute force.

  2. Step 2: Identify optimal approach

    Bitmasking encodes letters as bits, and a trie built on word bitmasks allows fast traversal of valid subsets, ensuring efficient counting.

  3. Final Answer:

    Option A -> Option A

  4. Quick Check:

    Bitmask + trie approach is known optimal for this problem [OK]
Quick Trick: Bitmask + trie efficiently enumerates subsets [OK]
Common Mistakes:
MISTAKES
  • Thinking brute force is optimal
  • Using DP without bitmasking
  • Greedy approaches fail on subset constraints
Trap Explanation:
PITFALL
  • Brute force looks straightforward but is too slow; DP without bitmasking misses subset enumeration efficiency.
Interviewer Note:
CONTEXT
  • Tests if candidate recognizes bitmask + trie pattern for subset counting problems.
Master "Number of Valid Words for Each Puzzle" in Subsets & Combinations

3 interactive learning modes - each teaches the same concept differently

Try ItSolutionTrace

Want More Practice?

15+ quiz questions · All difficulty levels · Free

Free Signup - Practice All Questions
More Subsets & Combinations Quizzes
Combination Sum II (No Reuse, Duplicates) - Combination Sum II (No Reuse, Duplicates) - Quiz 3easy Combinations (Choose K from N) - Combinations (Choose K from N) - Quiz 3easy Combinations (Choose K from N) - Combinations (Choose K from N) - Quiz 13medium Count Number of Max Bitwise-OR Subsets - Count Number of Max Bitwise-OR Subsets - Quiz 13medium Count Number of Max Bitwise-OR Subsets - Count Number of Max Bitwise-OR Subsets - Quiz 4medium Matchsticks to Square - Matchsticks to Square - Quiz 6medium Partition to K Equal Sum Subsets - Partition to K Equal Sum Subsets - Quiz 7medium Subsets - Subsets - Quiz 12easy Subsets - Subsets - Quiz 15hard Subsets II (With Duplicates) - Subsets II (With Duplicates) - Quiz 11easy