最短超级串

/*
 * 思路：
 * 1. 使用回溯法生成所有字符串的排列组合。
 * 2. 使用Java Stream对每一个排列组合，检查是否每个字符串都是该组合的子字符串。
 * 3. 返回满足条件的最短组合。
 */
import java.util.*;
import java.util.stream.Collectors;

public class Solution {
    public String shortestSuperstring(String[] words) {
        List<String> permutations = new ArrayList<>();
        permute(words, 0, permutations);
        return permutations.stream()
                .filter(perm -> isValid(perm, words))
                .min(Comparator.comparingInt(String::length))
                .orElse("");
    }

    private void permute(String[] words, int start, List<String> result) {
        if (start == words.length - 1) {
            result.add(String.join("", words));
        } else {
            for (int i = start; i < words.length; i++) {
                swap(words, i, start);
                permute(words, start + 1, result);
                swap(words, i, start);
            }
        }
    }

    private void swap(String[] words, int i, int j) {
        String temp = words[i];
        words[i] = words[j];
        words[j] = temp;
    }

    private boolean isValid(String superstring, String[] words) {
        return Arrays.stream(words).allMatch(superstring::contains);
    }
}