Description
You're given strings J representing the types of stones that are jewels, and S representing the stones you have. Each character in Sis 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
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Note:
-
SandJwill consist of letters and have length at most 50. - The characters in
Jare distinct.
Solution
HashSet, time O(n), space O(n)
class Solution {
public int numJewelsInStones(String J, String S) {
if (J == null || S == null) {
return -1;
}
Set<Character> jewels = new HashSet<>();
for (int i = 0; i < J.length(); ++i) {
jewels.add(J.charAt(i));
}
int count = 0;
for (int i = 0; i < S.length(); ++i) {
if (jewels.contains(S.charAt(i))) {
++count;
}
}
return count;
}
}
