I need help in this problem. I have tried all the test cases on Udebug as well, they are passing. But Vjudge is not accepting my code.

import java.io.DataInputStream;
import java.io.FileInputStream;
import java.io.IOException;

class Investigation {
    static class Reader
    {
        final private int BUFFER_SIZE = 1 << 16;
        private DataInputStream din;
        private byte[] buffer;
        private int bufferPointer, bytesRead;

        public Reader()
        {
            din = new DataInputStream(System.in);
            buffer = new byte[BUFFER_SIZE];
            bufferPointer = bytesRead = 0;
        }

        public Reader(String file_name) throws IOException
        {
            din = new DataInputStream(new FileInputStream(file_name));
            buffer = new byte[BUFFER_SIZE];
            bufferPointer = bytesRead = 0;
        }

        public String readLine() throws IOException
        {
            byte[] buf = new byte[64]; // line length
            int cnt = 0, c;
            while ((c = read()) != -1)
            {
                if (c == '\n')
                    break;
                buf[cnt++] = (byte) c;
            }
            return new String(buf, 0, cnt);
        }

        public int nextInt() throws IOException
        {
            int ret = 0;
            byte c = read();
            while (c <= ' ')
                c = read();
            boolean neg = (c == '-');
            if (neg)
                c = read();
            do
            {
                ret = ret * 10 + c - '0';
            }  while ((c = read()) >= '0' && c <= '9');

            if (neg)
                return -ret;
            return ret;
        }

        public long nextLong() throws IOException
        {
            long ret = 0;
            byte c = read();
            while (c <= ' ')
                c = read();
            boolean neg = (c == '-');
            if (neg)
                c = read();
            do {
                ret = ret * 10 + c - '0';
            }
            while ((c = read()) >= '0' && c <= '9');
            if (neg)
                return -ret;
            return ret;
        }

        public double nextDouble() throws IOException
        {
            double ret = 0, div = 1;
            byte c = read();
            while (c <= ' ')
                c = read();
            boolean neg = (c == '-');
            if (neg)
                c = read();

            do {
                ret = ret * 10 + c - '0';
            }
            while ((c = read()) >= '0' && c <= '9');

            if (c == '.')
            {
                while ((c = read()) >= '0' && c <= '9')
                {
                    ret += (c - '0') / (div *= 10);
                }
            }

            if (neg)
                return -ret;
            return ret;
        }

        private void fillBuffer() throws IOException
        {
            bytesRead = din.read(buffer, bufferPointer = 0, BUFFER_SIZE);
            if (bytesRead == -1)
                buffer[0] = -1;
        }

        private byte read() throws IOException
        {
            if (bufferPointer == bytesRead)
                fillBuffer();
            return buffer[bufferPointer++];
        }

        public void close() throws IOException
        {
            if (din == null)
                return;
            din.close();
        }
    }
    public static void main(String[] args)throws IOException {
        Reader s=new Reader();
        int test=s.nextInt();
        int c=1;
        while(test--!=0){
            char a[]=Long.toString(s.nextLong()-1).toCharArray();
            char b[]=Long.toString(s.nextLong()).toCharArray();
            int m=s.nextInt();
            if(m>=100){
                System.out.println("Case "+c+": 0");
                c++;
                continue;
            }
            long r=solve(b,m);
            long l=solve(a,m);
//            System.out.println(l+" "+r);
            long ans=r-l;
            System.out.println("Case "+c+": "+ans);
            c++;
        }
    }
    public static long solve(char a[],int m){
        int n=a.length;
        long dp[][][][]=new long[n+1][m][m][2];
        dp[0][0][0][1]=1;
        for(int i=1;i<=n;i++){
            int cd=a[i-1]-48;
            for(int p=0;p<=9;p++){
                for(int j=0;j<m;j++){
                    int nj=(j*10+p)%m;
                    for(int k=0;k<m;k++){
                        int nk=(k+p)%m;
                        if(p<cd){
                            dp[i][nj][nk][0]+=dp[i-1][j][k][0]+dp[i-1][j][k][1];
                        }
                        else if(p==cd){
                            dp[i][nj][nk][0]+=dp[i-1][j][k][0];
                            dp[i][nj][nk][1]+=dp[i-1][j][k][1];
                        }
                        else{
                            dp[i][nj][nk][0]+=dp[i-1][j][k][0];
                        }
                    }
                }
            }
        }
        return dp[n][0][0][1]+dp[n][0][0][0];
    }
}

Here's the problem Link