# LeetCode - 771. Jewels and Stones

## 题目

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:

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

## 常规思路

class Solution {
public int numJewelsInStones(String J, String S) {
int count = 0;
for (int i = 0; i < S.length(); i++) {
if (J.indexOf(S.charAt(i)) >= 0)
count++;
}
return count;
}
}

## 另辟蹊径

class Solution {
public int numJewelsInStones(String J, String S) {
return S.replaceAll("[^" + J + "]", "").length();
}
}

Runtime: 1 ms
Memory Usage: 33.7 MB

Runtime: 7 ms
Memory Usage: 34.9 MB

## 相关链接

posted @ 2019-06-08 15:02  雨临Lewis  阅读(132)  评论(0编辑  收藏  举报