Submission #45661899

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Source Code Expand

#include <bits/stdc++.h>
#include <atcoder/scc>

using Num = long long int;
std::unordered_map<std::string, Num> names;
Num id {0};

Num reg(const std::string& s) {
    Num sid {0};

    if (names.find(s) == names.end()) {
        sid = id;
        names[s] = sid;
        ++id;
    } else {
        sid = names[s];
    }

    return sid;
}

void solve(std::istream& is, std::ostream& os) {
    Num n {0};
    is >> n;

    std::unordered_map<Num, Num> edges;
    std::vector<Num> froms;

    for(decltype(n) i{0}; i<n; ++i) {
        std::string s;
        std::string t;
        is >> s >> t;
        const Num sid = reg(s);
        const Num tid = reg(t);
        edges[sid] = tid;
    }

    atcoder::scc_graph g(id);
    for(const auto& [from, to] : edges) {
        g.add_edge(from, to);
    }

    for(const auto& vec : g.scc()) {
        if (vec.size() > 1) {
            os << "No\n";
            return;
        }
    }

    os << "Yes\n";
    return;
}

int main(void) {
    solve(std::cin, std::cout);
    return 0;
}

Submission Info

Judge Result