Task: Minimum positive multiple in base 10 using only 0 and 1
C#: using System;
using System.Collections.Generic;
using static System.Console;
 
class Program {
 
  static string B10(int n) {
    int[] pow = new int[n + 1], val = new int[29];
    for (int count = 0, ten = 1, x = 1; x <= n; x++) {
      val[x] = ten;
      for (int j = 0, t; j <= n; j++)
        if (pow[j] != 0 && pow[j] != x && pow[t = (j + ten) % n] == 0)
          pow[t] = x;
      if (pow[ten] == 0) pow[ten] = x;
      ten = (10 * ten) % n;
      if (pow[0] != 0) {
        x = n;
        string s = ""; 
        while (x != 0) {
          int p = pow[x % n];
          if (count > p) s += new string('0', count - p);
          count = p - 1;
          s += "1";
          x = (n + x - val[p]) % n;
        }
        if (count > 0) s += new string('0', count);
        return s;
      }
    } 
    return "1";
  }
 
  static void Main(string[] args) {
    string fmt = "{0,4} * {1,24} = {2,-28}\n";
    int[] m = new int[] { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10,
      95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105,
      297, 576, 594, 891, 909, 999, 1998, 2079, 2251, 2277, 2439, 2997, 4878 };
    string[] r = new string[m.Length]; 
    WriteLine(fmt + new string('-', 62), "n", "multiplier", "B10");
    var sw = System.Diagnostics.Stopwatch.StartNew();
    for (int i = 0; i < m.Length; i++) r[i] = B10(m[i]);
    sw.Stop();
    for (int i = 0; i < m.Length; i++) Write(fmt, m[i], decimal.Parse(r[i]) / m[i], r[i]);
    Write("\nTook {0}ms", sw.Elapsed.TotalMilliseconds);
  }
}

Java: import java.math.BigInteger;
import java.util.ArrayList;
import java.util.List;



public class MinimumNumberOnlyZeroAndOne {

    public static void main(String[] args) {
        for ( int n : getTestCases() ) {
            BigInteger result = getA004290(n);
            System.out.printf("A004290(%d) = %s = %s * %s%n", n, result, n, result.divide(BigInteger.valueOf(n)));
        }
    }
    
    private static List<Integer> getTestCases() {
        List<Integer> testCases = new ArrayList<>();
        for ( int i = 1 ; i <= 10 ; i++ ) {
            testCases.add(i);
        }
        for ( int i = 95 ; i <= 105 ; i++ ) {
            testCases.add(i);
        }
        for (int i : new int[] {297, 576, 594, 891, 909, 999, 1998, 2079, 2251, 2277, 2439, 2997, 4878} ) {
            testCases.add(i);
        }
        return testCases;
    }
    
    private static BigInteger getA004290(int n) {
        if ( n == 1 ) {
            return BigInteger.valueOf(1);
        }
        int[][] L = new int[n][n];
        for ( int i = 2 ; i < n ; i++ ) {
            L[0][i] = 0;
        }
        L[0][0] = 1;
        L[0][1] = 1;
        int m = 0;
        BigInteger ten = BigInteger.valueOf(10);
        BigInteger nBi = BigInteger.valueOf(n);
        while ( true ) {
            m++;
            
            if ( L[m-1][mod(ten.pow(m).negate(), nBi).intValue()] == 1 ) {
                break;
            }
            L[m][0] = 1;
            for ( int k = 1 ; k < n ; k++ ) {
                
                L[m][k] = Math.max(L[m-1][k], L[m-1][mod(BigInteger.valueOf(k).subtract(ten.pow(m)), nBi).intValue()]);
            }
            
        }
        
        
        BigInteger r = ten.pow(m);
        BigInteger k = mod(r.negate(), nBi);
        for ( int j = m-1 ; j >= 1 ; j-- ) {
            if ( L[j-1][k.intValue()] == 0 ) {
                
                
                r = r.add(ten.pow(j));
                k = mod(k.subtract(ten.pow(j)), nBi);
            }
        }
        if ( k.compareTo(BigInteger.ONE) == 0 ) {
            r = r.add(BigInteger.ONE);
        }
        return r;
    }

    private static BigInteger mod(BigInteger m, BigInteger n) {
        BigInteger result = m.mod(n);
        if ( result.compareTo(BigInteger.ZERO) < 0 ) {
            result = result.add(n);
        }
        return result;
    }

    @SuppressWarnings("unused")
    private static int mod(int m, int n) {
        int result = m % n;
        if ( result < 0 ) {
            result += n;
        }
        return result;
    }
    
    @SuppressWarnings("unused")
    private static int pow(int base, int exp) {
        return (int) Math.pow(base, exp);
    }
}