771. Jewels and Stones。

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

J是宝石类型，S是自己拥有的，需要看看自己手中的石头有多少是宝石。

查找一下就行了。

class Solution {
public:
int numJewelsInStones(string J, string S) {
int count = 0;
for(auto s : S) {
if(J.find(s)!=-1) {
count++;
}
}
return count;
}
};