LeetCode 771 Jewels and Stones (bits)

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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.

题目链接：https://leetcode.com/problems/jewels-and-stones/

题目分析：52个字符，一个long存即可

1ms时间击败98.65%，36MB空间击败88.65%

class Solution {
    
    public long bitVal(char ch) {
        return 1l << ((ch >= 'a' && ch <= 'z') ? ch - 'a' : ch - 'A' + 26);
    }
    
    public int numJewelsInStones(String J, String S) {
        long bits = 0;
        for (int i = 0; i < J.length(); i++) {
            bits |= bitVal(J.charAt(i));
        }
        int ans = 0;
        for (int i = 0; i < S.length(); i++) {
            ans += (bitVal(S.charAt(i)) & bits) == 0 ? 0 : 1;
        }
        return ans;
    }
}