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Solution: Jewels and Stones

Understand how to solve the Jewels and Stones problem using hash maps to count jewel stones efficiently. Learn to implement a case-sensitive solution that treats jewels as an allowlist and counts matches in stones. This lesson covers optimal time and space complexity for this pattern and helps build skills in applying hash-based lookups to similar coding challenges.

Statement

You are given two strings, jewels and stones. Each character in jewels represents a stone type that is a jewel, and each character in stones represents a stone you have. Count how many characters in stones belong to the set of characters in jewels.

Note: Matching is case-sensitive, so 'a' and 'A' are different types of stones.

Constraints:

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