Codeforces 101243 B Hanoi tower

题意：对于给定N个碟子的汉诺塔，问当三个柱子上的碟子数目第一次相同时，需要移动几步。数据保证N≡0(mod3)

思路：打表找规律。

// 打表代码import java.io.File;import java.io.FileInputStream;import java.io.FileWriter;import java.io.IOException;import java.io.PrintStream;import java.math.BigDecimal;import java.math.BigInteger;import java.util.ArrayList;import java.util.LinkedList;import java.util.Scanner;import java.util.prefs.PreferenceChangeListener;import javax.security.auth.x500.X500Principal;import javax.swing.InternalFrameFocusTraversalPolicy;public class Main {    public static void main(String args[]) throws IOException    {        Scanner cin = new Scanner(System.in);        try{cin=new Scanner(new FileInputStream("input.in"));}catch(Exception e){}        int n;        for(int T=3;T<=300;T+=3)        {            //n=cin.nextInt();            n=T;            int all=n;            n=n/3;            BigInteger ans = BigInteger.ONE;            BigInteger up =BigInteger.ONE;            if(all==3)            {                ans=BigInteger.valueOf(2);            }            else if(all%2==0)            {                for(int i=0;i<n;i++)                {                    //System.out.println(up);                    ans=ans.add(up);                    up=up.multiply(BigInteger.valueOf(2));                }                up=up.add(BigInteger.ONE);                for(int i=0;i<n-1;i++)                {                    //System.out.println(up);                    ans=ans.add(up);                    up=up.multiply(BigInteger.valueOf(2));                }            }            else             {                for(int i=0;i<n-1;i++)                {                    //System.out.println(up);                    ans=ans.add(up);                    up=up.multiply(BigInteger.valueOf(2));                }                up=up.add(BigInteger.ONE);                for(int i=0;i<n;i++)                {                    //System.out.println(up);                    ans=ans.add(up);                    up=up.multiply(BigInteger.valueOf(2));                    if(i==n-2)up=up.subtract(BigInteger.ONE);                }            }            String aaString = ans.toString();            //System.out.println(ans);            FileWriter fileWriter = new FileWriter(new File("output.txt"));              ///String s = new String("This is a test!  \n" + "aaaa");             // fileWriter.write(aaString);             System.out.println("\""+ans+"\",");        }    }}

//C++ ac代码#include <bits/stdc++.h>#include <cstdio>#include <cstring>#include <cmath>#include <algorithm>#include <vector>#include <string>#include <map>#include <set>#include <cassert>using namespace std;typedef long long ll;typedef pair<int, int> pii;string ans[120] = { "2","9","38","135","542","2079","8318","32895","131582","524799","2099198","8390655","33562622","134225919","536903678","2147516415","8590065662","34359869439","137439477758","549756338175","2199025352702","8796095119359","35184380477438","140737496743935","562949986975742","2251799847239679","9007199388958718","36028797153181695","144115188612726782","576460752840294399","2305843011361177598","9223372039002259455","36893488156009037822","147573952598266347519","590295810393065390078","2361183241469182345215","9444732965876729380862","37778931863094600663039","151115727452378402652158","604462909807864343166975","2417851639231457372667902","9671406556919232420904959","38685626227676929683619838","154742504910681330455412735","618970019642725321821650942","2475880078570795734170337279","9903520314283182936681349118","39614081257132309534260330495","158456325028529238137041321982","633825300114115263698305023999","2535301200456461054793220095998","10141204801825837463773439328255","40564819207303349855093757313022","162259276829213372398777265029119","649037107316853489595109060116478","2596148429267413850294045183574015","10384593717069655401176180734296062","41538374868278621172359158709616639","166153499473114484689436634838466558","664613997892457937028364282443595775","2658455991569831748113457129774383102","10633823966279326985536299491456450559","42535295865117307942145197965825802238","170141183460469231740910675752738881535","680564733841876926963642703010955526142","2722258935367507707743890347601564794879","10889035741470030830975561390406259179518","43556142965880123323459523703856007479295","174224571863520493293838094815424029917182","696898287454081973173581491830620002713599","2787593149816327892694325967322480010854398","11150372599265311570770220319565615575597055","44601490397061246283080881278262462302388222","178405961588244985132295190914152631338270719","713623846352979940529180763656610525353082878","2854495385411919762116609717830853229927202815","11417981541647679048466438871323412919708811262","45671926166590716193865302138111296192894730239","182687704666362864775461208552445184771578920958","730750818665451459101843020821051317142553624575","2923003274661805836407372083284205268570214498302","11692013098647223345629481079581903386505809756159","46768052394588893382517924318327613546023239024638","187072209578355573530071668259090783432992763150335","748288838313422294120286673036363133731971052601342","2993155353253689176481146576088573851923483438612479","11972621413014756705924586304354295407693933754449918","47890485652059026823698344753189666898758131930628095","191561942608236107294793379012758667595032527722512382","766247770432944429179173514194124611452059698541363199","3064991081731777716716694056776498445808238794165452798","12259964326927110866866776219678353547520673527267065855","49039857307708443467467104878713414190082694109068263422","196159429230833773869868419485143095817481649838694072319","784637716923335095479473677940572383269926599354776289278","3138550867693340381917894711643447289308309891028789231615","12554203470773361527671578846573789157233239564115156926462","50216813883093446110686315385819787653847372230899364003839","200867255532373784442745261543279150615389488923597456015358","803469022129495137770981046171215126561215611592144769253375" };int main(){    int n;    freopen("input.txt", "r", stdin);    freopen("output.txt", "w", stdout);        while (cin >> n)    {        n /= 3;        n--;        cout << ans[n] << endl;    }}