题解 | #提取不重复的整数#

include<iostream>
#include<string>
#include<unordered_set>
#include<algorithm>
using namespace std;

int main()
{
    int num = 0;
    string ans;
    cin >> num;
    unordered_set<char> nums;
    string str = to_string(num);
    reverse(str.begin(), str.end());
    for (char c : str)
    {
        if(!nums.count(c)) //如果nums中不存在c
        {
            ans += c;
            nums.insert(c);
        }
    }
    cout<<stoi(ans);
    return 0;
}