小明的字符串(kmp)

import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        String str1 = scanner.nextLine();
        String str2 = scanner.nextLine();
        int[] next = kmpNext(str2);
        int temp;
        for (int i = str2.length(); i > 0; i--) {
            temp = kmpSearch(str1, str2.substring(0, i), next);
            if (temp != -1) {
                System.out.println(temp);
                break;
            }
        }
    }
    private static int kmpSearch(String str1, String str2, int[] next) {
        int j = 0;
        for (int i = 0; i < str1.length(); i++) {
            while (j > 0 && str1.charAt(i) != str2.charAt(j))
                j = next[j - 1];
            if (str1.charAt(i) == str2.charAt(j))
                j++;
            if (j == str2.length()) return str2.length();
        }
        return -1;
    }
    private static int[] kmpNext(String str2) {
        int[] next = new int[str2.length()];
        int j = 0;
        for (int i = 1; i < str2.length(); i++) {
            while (j > 0 && str2.charAt(i) != str2.charAt(j))
                j = next[j - 1];
            if (str2.charAt(i) == str2.charAt(j))
                j++;
            next[i] = j;
        }
        return next;
    }
}