package string;import java.util.ArrayList;import java.util.List;public class Main {    // 求最长公共子串长度    public int getMaxLen(String s1, String s2){        if(s1 == null || s2 == null){            return 0;        }        int m = s1.length();        int n = s2.length();        // a[i][j]表示以s1中以i-1结尾，s2中以j-1结尾的最长公共子串长度        int[][] a = new int[m+1][n+1];        int maxLen = 0;        for(int i = 1; i <= m; i++){            for(int j = 1; j <= n; j++){                if(s1.charAt(i-1) == s2.charAt(j-1)){                    a[i][j] = a[i-1][j-1]+1;                }else{                    a[i][j] = 0;                }                maxLen = Math.max(maxLen, a[i][j]);            }        }        return maxLen;    }        // 求最长公共子串    public List<String> getMaxSubString(String s1, String s2){        List<String> res = new ArrayList<String>();        if(s1 == null || s2 == null){            return res;        }        int m = s1.length();        int n = s2.length();        int maxLen = 0;        // a[i][j]表示以s1中以i-1结尾，s2中以j-1结尾的最长公共子串的长度        int[][] a = new int[m+1][n+1];        for(int i = 1; i <= m; i++){            for(int j = 1; j <= n; j++){                a[i][j] = s1.charAt(i-1) == s2.charAt(j-1) ? a[i-1][j-1]+1 : 0;                if(a[i][j] == maxLen){                    res.add(s1.substring(i-a[i][j], i));                } else if(a[i][j] > maxLen){                    res = new ArrayList<String>();                    res.add(s1.substring(i-a[i][j], i));                    maxLen = a[i][j];                }            }        }        return res;    }        public static void main(String[] args) {        Main m = new Main();//        String s1 = "bab";//        String s2 = "caba";        String s1 = "123456abcd567";        String s2 = "234dddabc45678";        System.out.println(m.getMaxLen(s1, s2));        System.out.println(m.getMaxSubString(s1, s2));    }}