Tags: "leetcode", "hashmap", "char-map", access_time 2-min read

Jewels and Stones

Created: May 2, 2020 by [lek-tin]

Last updated: May 2, 2020

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:

1. S and J will consist of letters and have length at most 1.
2. The characters in J are distinct.

Solution

class Solution {
    public int numJewelsInStones(String J, String S) {
        boolean[] lookup = new boolean[52];
        for (int i = 0; i < J.length(); i++) {
            char c = J.charAt(i);
            int index = 0;
            if (c >= 'a') {
                index = 26 + c - 'a';
            } else {
                index = c - 'A';
            }
            lookup[index] = true;
        }

        int count = 0;

        for (int i = 0; i < S.length(); i++) {
            char c = S.charAt(i);
            int index = 0;
            if (c >= 'a') {
                index = 26 + c - 'a';
            } else {
                index = c - 'A';
            }
            if (lookup[index] == true) count++;
        }

        return count;
    }
}