771. Jewels and Stones

Question

You’re given strings jewels representing the types of stones that are jewels, and stones representing the stones you have. Each character in stones is a type of stone you have. You want to know how many of the stones you have are also jewels.

Letters are case sensitive, so "a" is considered a different type of stone from "A".

Solution

数组统计，先遍历宝石，记录宝石的位置。
然后遍历石头，如果对应的位置已被记录则计数加一。

Code

class Solution {
    public int numJewelsInStones(String jewels, String stones) {
        int ret = 0;
        int[] bin = new int[58];
        for(char c : jewels.toCharArray()){
            bin[c-'A']++;
        }
        
        for(char c : stones.toCharArray()){
            if(bin[c-'A'] != 0) ret++;
        }
        return ret;
    }
}