Submission #785362

#	Time	Username	Problem	Language	Result	Execution time	Memory
785362		drdilyor	Highway Tolls (IOI18_highway)	C++17	51 / 100	285 ms	262144 KiB

highway

#include <bits/stdc++.h>
#include "highway.h"
#ifdef ONPC
    #include "t_debug.cpp"
#else
    #define debug(...) 42
#endif
using namespace std;
//namespace pbds = __gnu_pbds;
using ll = long long;
const int inf = 1e9;
const ll infl = 1e18;
const int RANDOM = chrono::high_resolution_clock::now().time_since_epoch().count();
mt19937 rng(RANDOM);
template<typename T, typename U> istream& operator>>(istream& is, pair<T, U>& p) { return is >> p.first >> p.second; }
template<typename Cont> int sz(const Cont& cont) { return int(cont.size()); }
template<typename Func> struct ycom { Func f; template<typename... T> auto operator()(T&&... args) { return f(*this, args...); } }; template<typename Func> ycom(Func) -> ycom<Func>;
template<typename T> typename vector<T>::iterator operator+(const vector<T>& x, int i) { return x.begin() + i ;};
const string fileio = "";
constexpr int tests = 1, nmax = 2e5, nlog = __lg(nmax), mod = 1e9+7;

void find_pair(int32_t n, std::vector<int32_t> u, std::vector<int32_t> v, int32_t a, int32_t b) {
    int m = u.size();
    vector<vector<pair<int,int>>> adj(n);

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

    ll base = ask(vector(m, 0));
    int len = base / a;

    auto mark_subtree = [&](auto& dfs, vector<int>& w, int i, int p)->void{
        for (auto[e, ei] : adj[i]) {
            if (e == p) continue;
            w[ei] = 1;
            dfs(dfs, w, e, i);
        }
    };

    auto find_path_from_root = [&](int root, int p, int len) {
        if (len == 0) {
            return root;
        }

        vector<pair<int,int>> level;
        auto dfs = [&](auto& dfs, int i, int p, int dep)->void{
            for (auto [e, ei] : adj[i]) {
                if (e == p) continue;
                if (dep+1 == len) {
                    level.emplace_back(e, ei);
                    continue;
                }
                dfs(dfs, e, i, dep+1);
            }
        };
        dfs(dfs, root, p, 0);

        int l = 0, r = level.size()-1;
        while (l < r) {
            int mid = (l + r) / 2;
            vector<int> w(m);
            for (int i = l; i <= mid; i++) {
                w[level[i].second] = 1;
            }
            ll toll = ask(w);
            assert(toll == base || toll == base - a + b);
            if (toll == base) {
                l = mid+1;
            } else r = mid;
        }
        return level[l].first;
    };

    int l = 0, r = m-1;
    while (l < r) {
        int mid = (l + r) / 2;
        vector<int> w(m);
        fill(w.begin() + l, w.begin() + mid+1, 1);
        ll toll = ask(w);
        if (toll == base) l = mid+1;
        else r = mid;
    }


    int left = u[l];
    int right = v[l];

    vector<int> w(m);
    mark_subtree(mark_subtree, w, left, right);
    int left_len = (ask(w) - base) / (b - a);

    answer(
            find_path_from_root(left, right, left_len),
            find_path_from_root(right, left, len - left_len - 1)
            );
}

• Subtask 1: 5 / 5
• Subtask 2: 7 / 7
• Subtask 3: 6 / 6
• Subtask 4: 33 / 33
• Subtask 5: 0 / 18
• Subtask 6: 0 / 31