执行操作后字典序最小的字符串

/*
 * This solution is similar to the Java version but uses Java Streams for concise and functional-style operations.
 */

import java.util.*;
import java.util.stream.*;

public class SmallestStringStream { 
    private static String add(String s, int a) {
        return IntStream.range(0, s.length())
            .mapToObj(i -> (i % 2 == 1) ? (char) (((s.charAt(i) - '0' + a) % 10) + '0') : s.charAt(i))
            .map(String::valueOf)
            .collect(Collectors.joining());
    }

    private static String rotate(String s, int b) {
        int n = s.length();
        b = b % n;
        return s.substring(n - b) + s.substring(0, n - b);
    }

    public static String findLexSmallestString(String s, int a, int b) {
        Set<String> visited = new HashSet<>();
        Queue<String> queue = new LinkedList<>();
        queue.offer(s);
        visited.add(s);
        String minString = s;

        while (!queue.isEmpty()) {
            String current = queue.poll();

            String added = add(current, a);
            if (visited.add(added)) {
                queue.offer(added);
                minString = Stream.of(minString, added).min(String::compareTo).orElse(minString);
            }

            String rotated = rotate(current, b);
            if (visited.add(rotated)) {
                queue.offer(rotated);
                minString = Stream.of(minString, rotated).min(String::compareTo).orElse(minString);
            }
        }

        return minString;
    }

    public static void main(String[] args) {
        String s = "5525";
        int a = 9;
        int b = 2;
        System.out.println(findLexSmallestString(s, a, b));  // Output: "2050"
    }
}