Problem:
Score: 300 points

Problem Statement

AtCoder Mart sells 1000000 of each of the six items below:

Riceballs, priced at 100 yen (the currency of Japan) each

Sandwiches, priced at 101 yen each

Cookies, priced at 102 yen each

Cakes, priced at 103 yen each

Candies, priced at 104 yen each

Computers, priced at 105 yen each

Takahashi wants to buy some of them that cost exactly X yen in total.
Determine whether this is possible.

(Ignore consumption tax.)

Constraints

1 \leq X \leq 100000

X is an integer.

Input

Input is given from Standard Input in the following format:

X

Output

If it is possible to buy some set of items that cost exactly X yen in total, print 1; otherwise, print 0.

Sample Input 1

615

Sample Output 1

1

For example, we can buy one of each kind of item, which will cost 100+101+102+103+104+105=615 yen in total.

Sample Input 2

217

Sample Output 2

0

No set of items costs 217 yen in total.

Solution in C# (Mono 4.6.2.0) (judge verdict: Accepted)

using System;

public class Program
{
    static void Main()
    {
        if(CalcCombination()) 
        {
            Console.WriteLine("1");
        }
        else
        {
            Console.WriteLine("0");
        }
    }

    /// <summary>
    /// 組み合わせ計算
    /// </summary>
    /// <returns></returns>
    private static bool CalcCombination()
    {
        double goukeiKingaku = double.Parse(Console.ReadLine().Trim());
        var hasuuKingaku = goukeiKingaku % 100;

        //100円のおにぎりのみで決まる場合は除外
        if (hasuuKingaku == 0) return true;

        //1個の場合は除外
        if (goukeiKingaku >= 100 && goukeiKingaku <= 105) return true;

        //全体の購入個数を仮決め
        //min:100*個数 = X、max:105*個数 = X
        for (int kosuu = (int)Math.Floor(goukeiKingaku / 100); kosuu >= Math.Floor(goukeiKingaku / 105); kosuu--) 
        {
            for (int i = kosuu; i >= 0; i--)
            {
                double sagaku = 3 * (kosuu - i) - hasuuKingaku;
                //103円のケーキを基準に+-2円の範囲で金額チェック
                if (sagaku > 0)
                {
                    if (CheckCombination((int)sagaku, kosuu - i)) return true;
                }
                else if (sagaku < 0)
                {
                    if (CheckCombination((int)Math.Abs(sagaku), kosuu - i)) return true;
                }
                else
                {
                    //103円のケーキのみで決まる
                    return true;
                }
            }

            //個数が減る場合は、+100円
            hasuuKingaku += 100;
        }
        return false;
    }

    /// <summary>
    /// 
    /// </summary>
    /// <param name="sagaku"></param>
    /// <param name="kosuu"></param>
    /// <returns></returns>
    private static bool CheckCombination(int sagaku, int kosuu)
    {
        //1円の個数をx、2円の個数をyとする。
        //x + y = kosuu
        //x + 2y = sagaku
        //これをとくと、x = 2 * kosuu - sagaku,y = sagaku - kosuu

        if (2 * kosuu - sagaku >= 0 && sagaku - kosuu >= 0)
        {
            return true;
        }

        return false;
    }
}