leetcode:宝石与石头

class Solution {
public int numJewelsInStones(String J, String S) {
char[] j=J.toCharArray();
char[] s=S.toCharArray();
int count[]=new int [‘z’-‘A’+1];//创建一个数组记录每个字符出现的次数
for(char ch:s){
count[ch-‘A’]++;
}
int sum=0;
for(char ch:j){
sum+=count[ch-‘A’];
}
return sum;
}
}