题解 | 字符串合并处理

#include <bits/stdc++.h>
using namespace std;
char cl(char s){
    int x;
    if(s>='0'&&s<='9')x=s-'0';
    else x=s-'a'+10;
    int a=x%2,b=(x/2)%2,c=(x/4)%2,d=(x/8)%2;
    x=(a<<3)+(b<<2)+(c<<1)+d;
    //cout<<x<<endl;
    if(x>=0&&x<=9)return '0'+x;
    else return 'A'+x-10;
}
int main(){
    string s,t,u;
    cin>>s>>t;
    u=s+t;s="";t="";
    int n=u.size();
    for(int i=0;i<u.size();i++){
        if(i%2==0)s.push_back(u[i]);
        else t.push_back(u[i]);
    }
      
    sort(s.begin(),s.end());
    sort(t.begin(),t.end());
    for(int i=0,k=0,l=0;i<n;i++){
        if(i%2==0)u[i]=s[k++];
        else  u[i]=t[l++];
    }
    for(int i=0;i<n;i++){
        if(u[i]>='0'&&u[i]<='9'||u[i]>='a'&&u[i]<='f'||u[i]>='A'&&u[i]<='F'){
            u[i]=cl(tolower(u[i]));
        }
    }
    cout<<u;
    return 0;
}