题解 | #字符串合并处理#

#include<iostream>
#include<string>
#include<algorithm>
#include<sstream>
#include<bitset>

using namespace std;

char bitToHex(string s){
    int t = (s[0]*1-48)*8+(s[1]*1-48)*4+(s[2]*1-48)*2+(s[3]*1-48)*1;
    char ch=' ';
    switch(t){
        case 10:
            ch='A';
            break;
        case 11:
            ch='B';
            break;
        case 12:
            ch='C';
            break;
        case 13:
            ch='D';
            break;
        case 14:
            ch='E';
            break;
        case 15:
            ch='F';
            break;
        default:
            ch=char(t+48);
    }

    return ch;
}

int main(){
    string str,s1,s2;

    while(cin>>str>>s1){
        str.append(s1);
        s1.clear();
        for(int i=1;i<str.size();i+=2){
            stringstream ss;
            ss<<str[i];
            s1.append(ss.str());
        }

        for(int i=0;i<str.size();i+=2){
            stringstream ss;
            ss<<str[i];
            s2.append(ss.str());
        }

        sort(s1.begin(),s1.end());
        sort(s2.begin(),s2.end());

        int size=str.size();
        str.clear();
        for(int i=0;i<size;i++){
            if(i%2==0){
                stringstream ss;
                ss<<s2[i/2];
                str.append(ss.str());
            }
            else{
                stringstream ss;
                ss<<s1[i/2];
                str.append(ss.str());
            }
        }

        string num="0123456789ABCDEF";
        for(int i=0;i<str.size();i++){
            if(isdigit(str[i]) || (str[i]>='A'&&str[i]<='F') ||(str[i]>='a'&&str[i]<='f')){
                stringstream ss;
                ss<<bitset<4> (num.find(toupper(str[i])));
                string s=ss.str();
                reverse(s.begin(),s.end());
                cout<<bitToHex(s);
            }
            else
                cout<<str[i];
        }
        str.clear();
        s1.clear();
        s2.clear();
        cout<<endl;
    }
    return 0;
}