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Codeforces April Fools Day Contest 2020 做题题解
|OI
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童 心 未 泯

估计也不会有人看愚人节比赛题解

但是真的好好玩啊qwq


Codeforces 1331A Is it rated?

Is it rated?

No!

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# Python 3
print("No")

Codeforces 1331B Limericks

5×7=355 \times 7 = 35.

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// C++
#include <bits/stdc++.h>
using namespace std;
int n;
int main(){
    cin >> n;
    for(int i = 2; i <= n; i++)
        if(n%i==0){cout << i << n/i << endl; return 0;}
}

Codeforces 1331C …And after happily lived ever they

这就太明显了:

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And they lived happily ever after
 5   4     3      2     1     0
And after happily lived ever they
 5    0      2      3    1    4

二进制换位.

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// C++
#include <bits/stdc++.h>
using namespace std;
#define at(a,j) ((a>>j)&1) 
int main(){
    int a; cin >> a; cout << (at(a,5)<<5) + (at(a,4)<<0) + (at(a,3)<<2) + (at(a,2)<<3) + (at(a,1)<<1) + (at(a,0)<<4) << endl;
    return 0;
}

Codeforces 1331D Again?


嗯？这也太明显了吧？一看不就是OEIS么。

（OEIS发现数列第一项对上了）

嗯？我怎么写代码？难不成还能访问网页？

（不对，一定有诈）

那只能是奇偶性了吧。

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# Python 3
print(int(input()[-1])%2)

Codeforces 1331E Jordan Smiley

愚蠢的码农题？

（不对，一定有诈）















居然没有。就是愚蠢的码农题

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# Python 3
s = [
"                          # # ###### #                          ",
"                      # ### # # #  # #####                      ",
"                    ### #   #   ## #    #  #                    ",
"                 #### # # #####    #### # ### #                 ",
"                ##      # #     ####    # # # ##                ",
"              #  ## ##### ### ### #  # ##   #  # #              ",
"             ###  #  #      # #   ####  ## ## ## ##             ",
"           ###### ## ## ### ### ###    ##  #  #   ###           ",
"          ############    #     #   # ##  ## ## #  ###          ",
"         #################### #######  ####  ##########         ",
"        ################################################        ",
"       ##################################################       ",
"       ##################################################       ",
"      ####################################################      ",
"     ######################################################     ",
"     ######################################################     ",
"    ########################################################    ",
"   ##########################################################   ",
"     ########################################################   ",
"       ############   #  ##############   # # #############     ",
"  ##     #########  #   ############### #       ########        ",
"  ####     #####   ## #   ############### ## ##  # ##       ##  ",
" #######     #   ###  ###  ########### #  #   ##         ###### ",
" #########     #  #  ## ##   ######### ## #####  #    ######### ",
" ############ ## ###     ###  #######   #  #    ### ########### ",
" #########     #   ### ###   ######## # ##### #   #  # ######## ",
"############ ### #  #  #   #  ######  #  #    ## ###   #########",
"###########   #  # ## ### ### #### # ### ####  ###   # #########",
"########### ###### ####    #  # #    # #  # ####   ### #########",
"###########     #  #  ### ###   # # ## ## #  #   #  #  #########",
"############ ## #### ## ###   # ###     #### # ###### ##########",
"###########   ###  #  #   ### #  ### ####  # ###   #   #########",
"#############     ## ### ## ### ##     #  ## ##  #   # #########",
"############## ## #    # #    # #  # # ## #   ## ## ############",
"############    #### # # # # #### ## #  # ###  ###   ###########",
"############# #  #   ###   ####   #  ##    #  ##   #############",
"################   ###   # ## ## ## ##  # ### #  #  ############",
"##################   # ######     #######   #   ################",
" ################  #    ##### # ###########   #  ############## ",
" ##############################    ############################ ",
" ########################### #  # ############################# ",
" ######################### #   ################################ ",
"  ########################   #   #############################  ",
"  #######  ################### ###############################  ",
"   ####### # ################   ##################### #######   ",
"   #######   #   ###########  # ########### ##### #    ######   ",
"   ####### # # #  # #   ## # ##  # #  # ##   ##     # #######   ",
"    ########   ##     #       ##   ##      # #  ### ########    ",
"     ####### #  #### #### ###  ###    ### ##### # #########     ",
"     ########## #  #  #   # #### ### ## #     #   #########     ",
"      ########    ## ## #    #   # #    ### #   ##########      ",
"       ######### ##   ##### ## # #   # ##   #############       ",
"       #########  ###  # #   ###   # ###  #   ###########       ",
"        #########   ####   ### ## #### #### ############        ",
"         ######### ##    # #      #    # ##############         ",
"          ############ # #### ## ## # ##  ############          ",
"           #############    ####    #    ############           ",
"             #################### #################             ",
"              ####################################              ",
"                ################################                ",
"                 ##############################                 ",
"                    ########################                    ",
"                      ####################                      ",
"                          ############                          "]
a,b = [int(i) for i in input().split(' ')]; print("IN" if s[a][b] is "#" else "OUT")

（这里直接借tourist的表来用了）


Codeforces 1331F Elementary!

毫无逻辑的样例。题目名，问题一定在题目名上。















元素周期表谁想得到啊喂

双关基本演绎法可海星

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# Python 3
s = ["AC", "AG", "AL", "AM", "AR", "AS", "AT", "AU", "BA", "BE", "BH", "BI",
     "BK", "BR",  "B", "CA", "CD", "CE", "CF", "CL", "CM", "CN", "CO", "CR",
     "CS", "CU",  "C", "DB", "DS", "DY", "ER", "ES", "EU", "FE", "FL", "FM",
     "FR",  "F", "GA", "GD", "GE", "HE", "HF", "HG", "HO", "HS",  "H", "IN",
     "IR",  "I", "KR",  "K", "LA", "LI", "LR", "LU", "LV", "MC", "MD", "MG",
     "MN", "MO", "MT", "NA", "NB", "ND", "NE", "NH", "NI", "NO", "NP",  "N",
     "OG", "OS",  "O", "PA", "PB", "PD", "PM", "PO", "PR", "PT", "PU",  "P",
     "RA", "RB", "RE", "RF", "RG", "RH", "RN", "RU", "SB", "SC", "SE", "SG",
     "SI", "SM", "SN", "SR",  "S", "TA", "TB", "TC", "TE", "TH", "TI", "TL",
     "TM", "TS",  "U",  "V",  "W", "XE", "YB",  "Y", "ZN", "ZR"]
def DFS(a):
    if a is "":
        return "YES"
    for j in s:
        if (len(j)==1 and a[0]==j[0] and DFS(a[1:])=="YES") or (len(a)>=2 and len(j)==2 and a[0]==j[0] and a[1]==j[1] and DFS(a[2:])=="YES"):
            return "YES"
    return "NO"
ss = input()
print(DFS(ss))

Codeforces 1331G Lingua Romana

最有意思的两道题之一。

一眼就知道是拉丁语

（translate.google.cn）

什么都没有…

这时TTL告诉我，他发现了Perl的方言包(???)…

然而Codeforces上是没有这个包的。需要手动翻译。

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// C++
#include <bits/stdc++.h>
using namespace std;
int x[12]; double a,b;
int main(){
    for(int i = 1; i <= 11; i++) cin >> x[i];
    for(int i = 11; i >= 1; i--){
        a = sqrt(abs(x[i])), b = 5*x[i]*x[i]*x[i];
        a+b <= 400 ? printf("f(%d) = %.2f\n",x[i],a+b) : printf("f(%d) = MAGNA NIMIS!\n",x[i]);
    }   return 0;
}

Codeforces 1331H It’s showtime

最有意思的两道题之一。

UnknownX语言。

编译一下。

WHAT THE FUCK DID I DO WRONG?

（google.com）

没啥结果

WHAT THE FUCK DID I DO WRONG programming language

（google.com）

嗯？

好吧开始现场学语言(ArnoldC)。这个语言关于如何输入介绍地很不明确，不过可以在Github Issue里搜索输入相关内容，然后可以看到一个新的Feature，进去读Feature源码就知道怎么输入了。

注意变量要开在外边。

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IT'S SHOWTIME

HEY CHRISTMAS TREE n
YOU SET US UP 0
 
GET YOUR ASS TO MARS n
DO IT NOW
I WANT TO ASK YOU A BUNCH OF QUESTIONS AND I WANT TO HAVE THEM ANSWERED IMMEDIATELY
 
 
HEY CHRISTMAS TREE mod
YOU SET US UP 0
GET TO THE CHOPPER mod
HERE IS MY INVITATION n
I LET HIM GO 1000
ENOUGH TALK
 
GET TO THE CHOPPER n
HERE IS MY INVITATION n
GET DOWN mod
HE HAD TO SPLIT 1000
ENOUGH TALK
 
 
HEY CHRISTMAS TREE ans
YOU SET US UP 1
 
HEY CHRISTMAS TREE even
YOU SET US UP 0
GET TO THE CHOPPER even
HERE IS MY INVITATION n
GET UP 1
I LET HIM GO 2
ENOUGH TALK
 
HEY CHRISTMAS TREE now
YOU SET US UP 0
 
 
STICK AROUND n
 
GET TO THE CHOPPER now
HERE IS MY INVITATION n
I LET HIM GO 2
GET DOWN even
GET UP 2
I LET HIM GO 2
ENOUGH TALK
 
BECAUSE I'M GOING TO SAY PLEASE now
GET TO THE CHOPPER ans
HERE IS MY INVITATION ans
YOU'RE FIRED n
I LET HIM GO mod
ENOUGH TALK
YOU HAVE NO RESPECT FOR LOGIC
 
GET TO THE CHOPPER n
HERE IS MY INVITATION n
GET DOWN 1
ENOUGH TALK
 
CHILL
 
TALK TO THE HAND ans
 
YOU HAVE BEEN TERMINATED

比赛体验

开场网卡交不了A题；B没思路；C简直是在送；D简直是在送。

发现过B的人还不少，回来看B。

Limericks: n. 五行打油诗(幽默短诗，起始两长句押韵，中间两短句押韵，最后一长句与开头两句押韵);

（google.com）

（baidu.com）

和每个句子的单词数有关系？

还是没思路。

（OEIS.org）

Limericks?

还是没思路。

嗯？就是求一个2个因数的因数分解。

看了一眼E。愚蠢的码农题，下一个。F没思路，开G。

（复制代码，语言UnknownX，提交！）

Compilation Error

不对，G好像是拉丁语。UnknownX是H题的。搞混了。

TTL去翻译拉丁语了。我开始肝H。然后就码了大概是一个小时…

嗯，交了G和H。看F。这个F要不是别人说我还真想不出来…

比赛结束。还不错，就F不会，E不想码（一定有诈）。

等等我G呢？

G题我居然默认语言还是UnknownX。

愚人节喜提CE！


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