Submission #730097

#	Time	Username	Problem	Language	Result	Execution time	Memory
730097		t6twotwo	Highway Tolls (IOI18_highway)	C++17	12 / 100	313 ms	262144 KiB

highway

#include "highway.h"
#include <bits/stdc++.h>
using namespace std;
void find_pair(int N, vector<int> U, vector<int> V, int A, int 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);
    }
    vector<int> a(M);
    int64_t dis = ask(a);
    vector<int> P(N, -1), T;
    auto dfs = [&](auto dfs, int x, int p, int dep) -> void {
        if (dis / A == dep) {
            T.push_back(x);
        }
        for (auto [y, z] : adj[x]) {
            if (y != p) {
                P[y] = z;
                dfs(dfs, y, x, dep + 1);
            }
        }
    };
    dfs(dfs, 0, -1, 0);
    int K = T.size();
    int lo = 0, hi = K - 1;
    while (lo < hi) {
        int x = (lo + hi) / 2;
        for (int i = lo; i <= x; i++) {
            a[P[T[i]]] = 1;
        }
        int64_t y = ask(a);
        for (int i = lo; i <= x; i++) {
            a[P[T[i]]] = 0;
        }
        if (y > dis) {
            hi = x;
        } else {
            lo = x + 1;
        }
    }
    answer(0, T[lo]);
}

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