题解 | #字符个数统计#

用 HashSet 处理。 但内存占用怎么这么多...

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        while (sc.hasNext()) {
            String input = sc.next();
            int length = input.length();
            // set to hold each distinct chars
            Set<Character> charSet = new HashSet<>(length);
            for (int i = 0; i < length; i++) {
                charSet.add(input.charAt(i));
            }

            // size of the set is the distinct char count
            System.out.println(charSet.size());
        }
    }
}