题解

#include<bits/stdc++.h>
using namespace std;
string s1,s2,s3,s4,s;
int main()
{
cin>>s;
for(int i=0;i<s.size();i++)
if(s[i]>=97&&s[i]<=122) s1=s1+s[i];
else if(s[i]>=65&&s[i]<=90) s2=s2+s[i];
else if(s[i]>=48&&s[i]<=57) s3=s3+s[i];
else s4=s4+s[i];
sort(s1.begin(),s1.end());
sort(s2.begin(),s2.end());
sort(s3.begin(),s3.end());
sort(s4.begin(),s4.end());
cout<<s1<<s2<<s3<<s4;
return 0;
}