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".

int numJewelsInStones(char* J, char* S) 
{
    int hash[128] = {0};
    int len = strlen(S);
    int cnt = 0;
    for(int i = 0;i < len;i++)
        hash[S[i]] += 1;
    
    for(int i = 0;i < strlen(J);i++)
        cnt +=hash[J[i]];
    
    return cnt;
}