【蓝桥杯】子串分值 (Java)

import java.util.ArrayList;
import java.util.Scanner;

public class Main {
    
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        String input=scan.next();
        char []arr=input.toCharArray();
//        //检验 记录每次的last next
//        ArrayList list = new ArrayList<>();
//        char []arr=new char[]{'a','b','c','d','a','b','c','d'};
        long last=0;
        long next=1;
        long sum=0;
        char c=' ';
        for (int i = 0; i < arr.length; i++) {//第i个字符的贡献值
            c=arr[i];
            //寻找上一个
            if (i==0){
                last=-1;
            }
            else{
                for (int j = i-1; j >=0 ; j--) {
                    if (c==arr[j]){
                        last=j;
                        break;//找到上一个c 并退出本循环
                    }
                    else{
                        last=-1;
                    }
                }
            }
            //没有下一个 下标为arr.length
            if (i==arr.length-1){
                next=arr.length;
            }
            else{
                for (int j =i+1; j