题解 | #公共子串计算#

30，10等下试试滑动窗口

import java.math.*;
//import java.lang.*;

public class Main{
    public static void main(String[]args){
        Scanner input = new Scanner(System.in);
        String str1 = input.nextLine();
        String str2 = input.nextLine();
        //String str1 = "baaabbabababbaabbaaaaaabbaabaabaaabbabbbbaabbaaabbbbbabababaaaaabbbbbabbbabaababaa";
        //String str2 = "bbbbbababbabaabbaabba";
        int line1 = str1.length();
        int lesline = 0;
        int linelength = 0;
        int line2 = str2.length();
        
        
        if(line1 > line2){
            lesline = line2;
        }else{
            lesline = line1;
        }
        //分长短是因为长串会经历很多次无用分割
        
    //知道短长度之后，对比期间不用区分长短，因为对比是相互的
        for(int i = lesline; i > 0; i--){ //指定字符串长度
            //int flag1 = 1;
            String a="";
            for(int ii = 0; ii <= line1; ii++){ //指定字符首所在位置
                if(ii+i > line1){ //ii+i > lesline || 
                    break;
                }
                             a = str1.substring(ii,ii+i);
                    if((str2.indexOf(a) != -1) && (i >= linelength)){
                            System.out.println(i);
                            linelength = i;
                                 break;
                             }
            }
            if((str2.indexOf(a)!=-1) && (i >= linelength)){
                                break;
                             }
               
            
        }
        //System.out.println(linelength);
        if(linelength == 0){
                                System.out.println(linelength);
                             }
    }
}