771. Jewels and Stones
Tags: ‘Hash Table’
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:
Input: J = "aA", S = "aAAbbbb" Output: 3
Example 2:
Input: J = "z", S = "ZZ" Output: 0
Note:
SandJwill consist of letters and have length at most 50.- The characters in
Jare distinct.
Solution
public int numJewelsInStones(String J, String S) {
Set<Character> set = new HashSet<>();
for (char c : J.toCharArray()) {
set.add(c);
}
int sum = 0;
for (char c : S.toCharArray()) {
if (set.contains(c)) sum++;
}
return sum;
}