Jewels and Stones

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Problem

You’re given strings J representing the types of stones that are jewels, and S representing the stones you have. Each character in S is a type of stone you have. You want to know how many of the stones you have are also jewels.

The letters in J are guaranteed distinct, and all characters in J and S are letters. Letters are case sensitive, so "a" is considered a different type of stone from "A".

Example 1

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Input: J = "aA", S = "aAAbbbb"
Output: 3

Example 2

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Input: J = "z", S = "ZZ"
Output: 0

Note

  • S and J will consist of letters and have length at most 50.
  • The characters in J are distinct.

My Answer

  • HashSet을 이용하자.
  • J를 순회하면서, 문자를 HashSet에 저장하고, S를 순회하면서 HashSet에 포함되어 있는지 확인.
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class Solution {
    public int numJewelsInStones(String J, String S) {
        Set<Character> hashset = new HashSet<>();
        
        for(int i=0;i<J.length();i++) {
            hashset.add(J.charAt(i));
        }
        
        int total = 0;
        for(int i=0;i<S.length();i++) {
            if ( hashset.contains(S.charAt(i))) total++;
        }
        
        return total;
    }
}

참고