Prefix.java

import java.util.*;

public class Prefix {

    public static String longestCommonPrefix(String[] strs) {
        if (strs == null || strs.length == 0) return "";

        String prefix = strs[0];

        for (int i = 1; i < strs.length; i++) {
            // Reduce prefix until current string starts with it
            while (!strs[i].startsWith(prefix)) {
                prefix = prefix.substring(0, prefix.length() - 1);
                if (prefix.isEmpty()) return "";
            }
        }

        return prefix;
    }

    public static void main(String[] args) {
        // Example Input
        String[] strs1 = {"flower", "flow", "flight"};
        String[] strs2 = {"dog", "racecar", "car"};

        System.out.println("Output 1: " + longestCommonPrefix(strs1)); // fl
        System.out.println("Output 2: " + longestCommonPrefix(strs2)); // ""
    }
}