197C - Lexicographically Maximum Subsequence - CodeForces Solution

#include <bits/stdc++.h>

using namespace std;

int main() {
    string s;
    cin >> s;

    auto f = [&](int pos) -> pair<int, int> {
        int maxPos = -1;
        int cnt = 0;
        for (int i = pos; i < s.size(); i++) {
            if (maxPos == -1 || s[i] > s[maxPos]) {
                maxPos = i;
                cnt = 1;
            } else if (s[i] == s[maxPos]) {
                cnt++;
                maxPos = i;
            }
        }

        return {cnt, maxPos};
    };

    string ans;
    int l = 0;
    while (l < s.size()) {
        auto [cnt, pos] = f(l);
        for (int i = 0; i < cnt; i++)
            ans += s[pos];
        l = pos + 1;
    }

    cout << ans;
}/*1690811307.0023844*/