最长回文子串

/**
 * This solution utilizes Java Stream API to find the longest palindromic substring.
 * However, due to the functional nature of streams, dynamic programming table implementation is less straightforward.
 * We implement a similar solution but in a more functional style where possible.
 */
import java.util.stream.IntStream;
 
public class SolutionStream {
    public String longestPalindrome(String s) {
        int n = s.length();
        if (n <= 1) return s;
 
        boolean[][] dp = new boolean[n][n];
        int[] maxLenStart = {1, 0}; // maxLen, start
 
        IntStream.range(0, n).forEach(i -> dp[i][i] = true);
 
        IntStream.range(0, n - 1).filter(i -> s.charAt(i) == s.charAt(i + 1)).forEach(i -> {
            dp[i][i + 1] = true;
            maxLenStart[0] = 2;
            maxLenStart[1] = i;
        });
 
        IntStream.range(3, n + 1).forEach(len ->
            IntStream.range(0, n - len + 1).forEach(i -> {
                int j = i + len - 1;
                if (s.charAt(i) == s.charAt(j) && dp[i + 1][j - 1]) {
                    dp[i][j] = true;
                    maxLenStart[0] = len;
                    maxLenStart[1] = i;
                }
            })
        );
 
        return s.substring(maxLenStart[1], maxLenStart[1] + maxLenStart[0]);
    }
}