771. Jewels and Stones

Problem

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".

  Example 1:

Input: jewels = "aA", stones = "aAAbbbb"
Output: 3

Example 2:

Input: jewels = "z", stones = "ZZ"
Output: 0

  Constraints:

• 1 <=&nbsp;jewels.length, stones.length <= 50

• jewels and stones consist of only English letters.

• All the characters of jewels are unique.

Solution (Java)

class Solution {
    public int numJewelsInStones(String jewels, String stones) {
        int[] x = new int[60];
        int count = 0;
        int len = jewels.length();
        int len2 = stones.length();
        for (int i = 0; i < len; i++) {
            x[jewels.charAt(i) - 65]++;
        }
        for (int i = 0; i < len2; i++) {
            if (x[stones.charAt(i) - 65] == 1) {
                count++;
            }
        }
        return count;
    }
}

Explain:

nope.

Complexity:

• Time complexity : O(n).
• Space complexity : O(n).