C++代码

#include <iostream>
#include <bits/stdc++.h>
using namespace std;
int main()
{
ios::sync_with_stdio(0);
cin.tie(0);
string s;
cin >> s;
bool a[256] = {false};
for( int i = 0; i < s.size(); i++ ) a[( char )s[i]] = true;
for( int i = 127; i >= 0; i-- ) if( a[i] ) cout << ( char )i;
return 0;
}