第7回PAST G べき表現

問題へのリンク

C#のソース

using System;
using System.Collections.Generic;
using System.Linq;

class Program
{
    static string InputPattern = "InputX";

    static List<string> GetInputList()
    {
        var WillReturn = new List<string>();

        if (InputPattern == "Input1") {
            WillReturn.Add("6");
            //2
            //9 -3 
        }
        else if (InputPattern == "Input2") {
            WillReturn.Add("9193");
            //9
            //2187 27 1 -243 3 9 -81 6561 729 
        }
        else if (InputPattern == "Input3") {
            WillReturn.Add("10120190919012");
            //16
            //-1594323 9 -177147 -531441 1162261467 -4782969 387420489 -6561 -2187 2541865828329 -27 7625597484987 3486784401 10460353203 -94143178827 31381059609 
        }
        else {
            string wkStr;
            while ((wkStr = Console.ReadLine()) != null) WillReturn.Add(wkStr);
        }
        return WillReturn;
    }

    static void Main()
    {
        List<string> InputList = GetInputList();
        long N = long.Parse(InputList[0]);

        // 平衡3進数に変換
        var NumList = new List<long>();
        do {
            long Mod = N % 3;
            if (Mod == 0) {
                N /= 3;
                NumList.Add(0);
            }
            if (Mod == 1) {
                N /= 3;
                NumList.Add(1);
            }
            if (Mod == 2) {
                N++;
                N /= 3;
                NumList.Add(-1);
            }
        } while (N > 0);

        long BekiVal = 1;
        var AnswerList = new List<long>();
        foreach (long EachNum in NumList) {
            AnswerList.Add(EachNum * BekiVal);
            BekiVal *= 3;
        }

        // 0はRemoveする
        AnswerList.RemoveAll(pX => pX == 0);

        Console.WriteLine(AnswerList.Count);
        string[] AnswerStr = Array.ConvertAll(AnswerList.ToArray(), pX => pX.ToString());
        Console.WriteLine(string.Join(" ", AnswerStr));
    }
}

解説

平衡3進数に変換してます。