제출 #1079504

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
1079504		skittles1412	Highway Tolls (IOI18_highway)	C++17	0 / 100	8 ms	1112 KiB

highway

#include "bits/extc++.h"

using namespace std;

template <typename T, typename... U>
void dbgh(const T& t, const U&... u) {
    cerr << t;
    ((cerr << " | " << u), ...);
    cerr << endl;
}

#ifdef DEBUG
#define dbg(...)                                              \
    cerr << "L" << __LINE__ << " [" << #__VA_ARGS__ << "]: "; \
    dbgh(__VA_ARGS__)
#else
#define dbg(...)
#define cerr   \
    if (false) \
    cerr
#endif

using ll = long long;

#define endl "\n"
#define long int64_t
#define sz(x) int(std::size(x))

inline void init_io() {
    cin.tie(nullptr);
    cin.exceptions(ios::failbit);
    ios_base::sync_with_stdio(false);
}

template <typename T>
vector<T> iota(int n, T x) {
    vector<T> ans(n);
    iota(begin(ans), end(ans), x);
    return ans;
}

template <typename T>
vector<T>& operator+=(vector<T>& a, const vector<T>& b) {
    a.insert(end(a), begin(b), end(b));
    return a;
}

template <typename T>
vector<T> operator+(vector<T> a, const vector<T>& b) {
    return a += b;
}

template <typename Cb>
struct CmpByKey {
    Cb cb;

    CmpByKey(Cb cb) : cb(cb) {}

    template <typename T>
    bool operator()(const T& a, const T& b) const {
        return cb(a) < cb(b);
    }
};

template <typename T, typename Cb>
T first_true(T l, T r, const Cb& cb) {
    while (l < r) {
        T mid = (l + r) / 2;

        if (cb(mid)) {
            r = mid;
        } else {
            l = mid + 1;
        }
    }

    return l;
}

template <typename T, typename Cb>
T last_true(T l, T r, const Cb& cb) {
    while (l < r) {
        T mid = (l + r + 1) / 2;

        if (cb(mid)) {
            l = mid;
        } else {
            r = mid - 1;
        }
    }

    return l;
}

ll ask(const std::vector<int>& w);
void answer(int s, int t);

vector<int> bfs(const vector<vector<pair<int, int>>>& graph, int src) {
    int n = sz(graph);

    vector dist(n, -1);
    queue<int> q;

    auto push = [&](int u, int d) -> void {
        if (dist[u] != -1) {
            return;
        }

        dist[u] = d;
        q.push(u);
    };

    push(src, 0);

    while (sz(q)) {
        int u = q.front();
        q.pop();

        for (auto& [v, _ei] : graph[u]) {
            push(v, dist[u] + 1);
        }
    }

    return dist;
}

void solve(int n, const vector<pair<int, int>>& edges, int wa, int wb) {
    int m = sz(edges);

    vector<vector<pair<int, int>>> graph(n);

    for (int i = 0; i < m; i++) {
        auto& [u, v] = edges[i];
        graph[u].emplace_back(v, i);
        graph[v].emplace_back(u, i);
    }

    long base = ask(vector<int>(m, 0));

    auto nodes_blocked = [&](const vector<int>& nodes) -> vector<int> {
        vector<int> cv(m);

        for (auto& u : nodes) {
            for (auto& [_v, ei] : graph[u]) {
                cv[ei] = true;
            }
        }

        return cv;
    };

    int root = first_true(0, n, [&](int x) -> bool {
        return ask(nodes_blocked(iota(x + 1, 0))) > base;
    });

    auto base_block = iota(root, 0);

    auto dist = bfs(graph, root);
    auto ord = iota(n, 0);
    sort(begin(ord), end(ord), CmpByKey([&](int u) -> int {
        return dist[u];
    }));

    int u1_ind = last_true(0, n, [&](int x) -> bool {
        return ask(nodes_blocked(vector(begin(ord) + x, end(ord))) +
                   base_block) > base;
    });
    int u2_ind = last_true(0, u1_ind, [&](int x) -> bool {
        return ask(nodes_blocked(vector(begin(ord) + x, begin(ord) + u1_ind)) +
                   base_block) > base;
    });

    answer(ord[u1_ind], ord[u2_ind]);
}

void find_pair(int n,
               vector<int> edges_u,
               vector<int> edges_v,
               int wa,
               int wb) {
    return solve(n, [&]() {
        vector<pair<int, int>> cv;

        for (int i = 0; i < n; i++) {
            cv.emplace_back(edges_u[i], edges_v[i]);
        }

        return cv;
    }(), wa, wb);
}

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