leetcode 771

leetcode 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

Note:

• S and J will consist of letters and have length at most 50.
• The characters in J are distinct.

思路： 取出每个S中的字符，判断J中是否包含这个字符，包含的话计数器加一

 

class Solution {
    public int numJewelsInStones(String J, String S) {
        int jLen = J.length();
        int sLen = S.length();
        
        if(jLen == 0 || sLen == 0 || J ==null || S == null) return 0;
        int count = 0; //count the jewels
        for(int i=0;i< sLen;i++) {
            char c= S.charAt(i);
            if(J.contains(String.valueOf(c))) count++;
        }
        
        return count;
    }
}