LRS.java

// longest repeated substring
public class LRS {
    public static String lcp(String s1, String s2) {
        int min = Math.min(s1.length(), s2.length());
        for (int i = 0; i < min; i++) {
            if (s1.charAt(i) != s2.charAt(i))
                return s1.substring(0, i);
        }
        return s1.substring(0, min);
    }

    public static String lrs(String string) {
        int l = string.length();
        String[] suffixes = new String[l];
        for (int i = 0; i < l; i++) {
            suffixes[i] = string.substring(i, l);
        }
        Sort.mergeSort(suffixes);
        String lrs = "";
        for (int i = 0; i < l - 1; i++) {
            String x = lcp(suffixes[i], suffixes[i + 1]);
            if (x.length() > lrs.length()) lrs = x;
        }
        return lrs;
    }

    public static void main(String[] args) {
        String s = args[0];
        System.out.println(lrs(s));
    }
}