The following code is for this problem

This program used 0.89s to pass all test cases. But I find other people use Java can achieve ~0.20s. So how to improve my code?

The idea is to establish a table for the recursive call to look up previously calculated the value.

import java.util.*;  public class Dice {   static double table[][];    public static double game(int s, int r, int d)   {     if(table[r][d] != -1) return table[r][d];     double a = (1 - (double)d/(double)s) * game(s, r - 1, d + 1);     double b = ((double)d/(double)s) * game(s, r - 1, d);     double sum = a + b;     table[r][d] = sum;     return sum;   }    public static void main(String[] args)   {     Scanner in = new Scanner(System.in);     int n = in.nextInt();     int s = in.nextInt();     int k = in.nextInt();     table = new double[n+1][n+1];      for(int i = 0; i < n+1; i++)      for(int j = 0; j < n+1; j++)        table[i][j] = (double)-1;      for(int i = 0; i < n+1; i++)      for(int j = 0; j < n+1; j++)       if(i + j < k)         table[i][j] = (double)0;      for(int j = 0; j < n+1; j++)      for(int i = k; i < n+1; i++)        table[j][i] = (double)1;      System.out.println(game(s, n, 0));    }  }