difficult：easy #771

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.

解法

#include<string>
int numJewelsInStones(std::string J, std::string S) {
    int num = 0;
    for (auto i = S.begin(); i < S.end(); i++) {
        if (J.find(*i) != std::string::npos)
            num++;
    }
    return num;
}

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