编码最短长度的字符串

/*
 * Problem: Encode the shortest length of a string using Java Streams
 * Idea: Similar to the standard Java solution but using Java Streams for operations where applicable.
 */
import java.util.stream.IntStream;
 
public class EncodeShortestLengthStream {
    public String encode(String s) {
        int n = s.length();
        String[][] dp = new String[n][n];
 
        IntStream.range(1, n + 1).forEach(len -> {
            IntStream.range(0, n - len + 1).forEach(i -> {
                int j = i + len - 1;
                String substr = s.substring(i, j + 1);
                dp[i][j] = substr;
 
                IntStream.range(i, j).forEach(k -> {
                    if ((dp[i][k] + dp[k + 1][j]).length() < dp[i][j].length()) {
                        dp[i][j] = dp[i][k] + dp[k + 1][j];
                    }
                });
 
                String pattern = findPattern(substr);
                if (pattern.length() < substr.length()) {
                    dp[i][j] = pattern;
                }
            });
        });
 
        return dp[0][n - 1];
    }
 
    private String findPattern(String s) {
        int n = s.length();
        return IntStream.rangeClosed(1, n / 2)
                .filter(k -> n % k == 0 && s.replace(s.substring(0, k), "").isEmpty())
                .mapToObj(k -> n / k + "[" + dpEncode(s.substring(0, k)) + "]")
                .findFirst()
                .orElse(s);
    }
 
    private String dpEncode(String s) {
        return encode(s);
    }
}