问题描述：
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
解决方案：
1 数组
var numJewelsInStones = function(J, S) {
var arr1=J.split("");
var arr2=S.split("");
var count=0;
for(var i=0;i<arr2.length;i++){
for(var j=0;j<arr1.length;j++){
if(arr2[i]==arr1[j]){
count++
}
}
}
return count
};
2 字符串方法
var numJewelsInStones = function(J, S) {
var count=0;
for(var i=0;i<S.length;i++){
if(J.indexOf(S.charAt(i))!==-1){
count++
}
}
return count
};
letCode(771 Jewels and Stones )
原文：https://www.cnblogs.com/lsqbubble/p/10316384.html