题解 | #字符串合并处理#

#include<bits/stdc++.h>

using namespace std;


int main(){
    
    string str1,str2;
    while(cin>>str1>>str2){
        string new_str = str1+str2;
        
        if(new_str.size()>2){
            //希尔排序
            for(int i=2;i<new_str.size();++i){
                if(new_str[i]<new_str[i-2]){
                    char ch = new_str[i];
                    int j=i-2;
                    for(j;new_str[j]>ch&&j>=0;j-=2){
                        new_str[j+2] = new_str[j];
                    }
                    new_str[j+2] = ch;
                }
            }
        }
        
        for(int i=0;i<new_str.size();++i){
            int num=-1;
            if(new_str[i]>='0'&&new_str[i]<='9'){
                num = new_str[i]-'0';
            }else if(new_str[i]>='A'&&new_str[i]<='F'){
                num = new_str[i]-'A'+10;
            }else if(new_str[i]>='a'&&new_str[i]<='f'){
                num = new_str[i]-'a'+10;
            }
            if(num>-1){
                bitset<4> b1(num);
                string tmp = b1.to_string();
                reverse(tmp.begin(), tmp.end());
                bitset<4> b2(tmp);
                int res_num = b2.to_ulong();
                if(res_num>=0&&res_num<=9)
                    new_str[i]='0'+res_num;
                else if(res_num>9&&res_num<16)
                    new_str[i]='A'+res_num-10;
            }
        }
        cout<<new_str<<endl;
    }

    return 0;
}