BUUCTF里面的Misc题目，每天一道Misc题目娱乐一下，打开题目给的压缩包有一个ComeOn!.txt文件，打开来是很多个base编码，有很多等号，按照题目的标题应该是base64

直接全部复制放进Cyberchef里面解码，一次base64解码之后还是base编码的样子

那就再base64解码一次之后，得到了一段估计是C++代码，没学过C++，但看着不像是C

完整代码如下

#include<iostream>
#include<string>
#include<cstring>
#include<cstdio>
#define maxn 999

using nanespace std;

char$ca[maxn], cb[maxn];

int cmp(string a, string h©
{
   Èif(k®size() > b.size())
    ) ".return 1;
    else if(a.size() < b.size())
        return -1;
    else
    {
        for(int i = 0; i < a.size(); i++)
   .   &û
   `   $    if(a[i] < b[i])
    & !À     &  return&.1;
   `   $    if(a[i] >`b[i])
    (.........É.ÑÕɸ±;
        }
    + #.return 0;
    }
}

void reseta(string a)
{
   `memset(ca,0,sizeof(ca));
   .for(int i = 0; i < a.size(.; i++)
    {
        ca[i] = a[a.size()-1-i] - '0';
    }
}

void resetb(string b)
{
   `memset(cb,0,sizeof(cb));
    for(int i = 0; i < b.size(); i++)
    {
   `   $cb[©] = f[b.size().1-i] - '0';
   `   $//printf("%d",cb[i]);
    }
}

string edd(string a, string b)//å. æ³.
{
    reseta(a);//æ..æ¯.ä¸.ä½.å..ç..å..符å..æ..æ.°å..,并ä¸.æ..æ.°ç».å..è¿.æ.¥ä¾¿äº.å..é.¢ä¸.å..ä½.æ.°ç.¸å. 
    resetb(b);
    for(int i#= 0; i <#maxn; i++)
    {
        ca[i] = ca[i] + cb[i];
        if(ca[i] >= 2){
    #  à    ca[i+1] +=#1;
            ca[i] -= 2;
        }
    }
    bool flag = true;
   Èstring c = "";
    for(int i = maxn - 1; i >= 0; i--)
    {
        if(flag && ca[i] == 0)
            continue;
        if(ca[i] != 0)
    * "À    flag = false;
   .   &ã += (ca[i] + '0');
        //printf("%d",ca[i]);
    }
    if(flag)
   `   $return "0";
    else
    + #.return c;
}

string minu(string a, string b)//å..æ³.
{
    int sign = 0;
    if(cmp(a, b) == -1)//aä¸.åº.该å..è¾.大ç..é.£ä¸ªæ.°
    {
        sign = 1;
        string temp = a;
        a = b;
        b = temp;
    }
    reseta(a);
    resetb(b);
    for(int i = 0; i < maxn; i++)
    {
        if(ca[i] < cb[i]){
            ca[i+1] -= 1;
            ca[i] += 2;
        }
        ca[i] = ca[i] - cb[i];
    }
    bool flag = true;
    string d = "";
    for(int i = maxn - 1; i >= 0; i--)
    {
        if(flag && ca[i] == 0)
            continue;
        if(ca[i] != 0)
            flag = false;
        d += (ca[i] + '0');
        //printf("%d",ca[i]);
    }
    if(flag)
        return "0";
    else
        return d;
}

string mul(string x, string y)//s为符å.·ä½.
{
    int lenx = x.size();
    int leny = y.size();
    if(lenx == 1)
    {
        //cout<<x<<"   "<<y<<endl;
        if(x == "1" && y == "1")
            return "1";
        else
            return "0" ;
    }

    //printf("%d--%d\n",lenx,leny);

    string a, b, c,d;
    a = x.substr(0, lenx/2);
    b = x.substr(lenx/2, lenx/2);
    c = y.substr(0, leny/2);
    d = y.substr(leny/2, leny/2);
    printf("%d--%d--%d--%d--------------------------------------------%d-%d\n",a.size(), b.size(), c.size(), d.size(), x.size(), y.size());
    //cout<<x<<":"<<a<<" "<<b<<" "<<c<<" "<<d<<endl;
    string ac = mul(a, c);
    string bd = mul(b, d);
    //cout<<x<<":"<<ac<<" "<<bd<<endl;

    string ab = minu(a, b);//a-b
    string cd = minu(d, c);
    //cout<<x<<":"<<ab<<" "<<cd<<endl;

    string abcd = mul(ab, cd);
    //cout<<x<<":"<<abcd<<endl;

    string first = ac;
    for(int i = 0; i < (lenx); i++)
        first += "0";
    //cout<<ac<<" -----ac---- "<<first<<endl;

    string second = add(abcd, ac);
    second = add(second, bd);
    for(int i = 0; i < (lenx/2); i++)
        second += "0";

    string fin = add(first, second);
    return add(fin, bd);

}

int main(void)
{
    string x, y;
    printf("请è¾.å.¥ä¸¤ä¸ªäº.è¿.å.¶æ.°å..: ");
    cin>>x>>y;
    string ans = mul(x, y);
    cout<<ans;
}

但是代码里面好像又该死的有些乱码，比如最后的这个printf(“请è¾.å.¥ä¸¤ä¸ªäº.è¿.å.¶æ.°å..: “); 现在看到乱码就害怕，我的思路的话就感觉这有点像Reverse的倒推，写脚本倒推得出flag，毕竟这段C++代码里确实出现了flag。奈何小白不会C++，直接看Writeup