移位字符串分组

/*
 * Leetcode 249: Group Shifted Strings using Java Streams
 * This solution leverages Java Streams for a more concise approach.
 */
 
import java.util.*;
import java.util.stream.Collectors;
 
public class SolutionStream {
    public List<List<String>> groupStrings(String[] strings) {
        return new ArrayList<>(
            Arrays.stream(strings)
                  .collect(Collectors.groupingBy(this::getShiftKey))
                  .values()
        );
    }
 
    private String getShiftKey(String str) {
        StringBuilder key = new StringBuilder();
        for (int i = 1; i < str.length(); i++) {
            int diff = str.charAt(i) - str.charAt(i - 1);
            if (diff < 0) {
                diff += 26;
            }
            key.append(diff).append(',');
        }
        return key.toString();
    }
 
    public static void main(String[] args) {
        SolutionStream sol = new SolutionStream();
        String[] strings = {"abc", "bcd", "acef", "xyz", "az", "ba", "a", "z"};
        List<List<String>> result = sol.groupStrings(strings);
        System.out.println(result);
    }
}