Submission #1607579

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Source Code Expand

#include <bits/stdc++.h>

using namespace std;

namespace {
    string s;
    void input() {
        cin >> s;
    }

    string& succ(string& x) {
        if (x.empty()) x.push_back('a');
        else if (x.back() == 'z') {
            x.pop_back();
            succ(x);
            x.push_back('a');
        } else {
            x.back()++;
        }
        return x;
    }

    bool includes(const string& s, const string& t) {
        int i = 0, j = 0;
        while (i < s.size() && j < t.size()) {
            if (s[i] == t[j]) j++;
            i++;
        }
        return j == t.size();
    }

    void solve() {
        string t = "a";
        while (true) {
            if (includes(s, t)) succ(t);
            else break;
        }
        cout << t << endl;
    }
}

int main() {
    input(); solve();
    return 0;
}

Submission Info

Judge Result