제출 #139422

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
139422		fredbr	통행료 (IOI18_highway)	C++17	51 / 100	391 ms	262148 KiB

highway

#include "highway.h"

#include <bits/stdc++.h>

using namespace std;

using ll = long long;

int const maxn = 90909;

struct Edge {
    int u, id;
};

vector<Edge> v[maxn];

vector<int> order;
vector<int> vt;

void dfs(int x, int p) {
    for (Edge e : v[x]) {
        if (e.u == p) continue;
        order.push_back(e.id);
        vt.push_back(e.u);
        dfs(e.u, x);
        order.push_back(e.id);
        vt.push_back(x);
    }
}

void find_pair(int n, vector<int> U, vector<int> V, int a, int b) {
    int m = U.size();

    for (int i = 0; i < m; i++) {
        v[U[i]].push_back(Edge{V[i], i});
        v[V[i]].push_back(Edge{U[i], i});
    }

    dfs(0, 0);

    ll total_cost = ask(vector<int>(m, 1));

    int l = 0, r = (int)order.size();

    while (r-l > 1) {
        int mid = (l+r)/2;

        vector<int> q(m, 0);
        for (int i = 0; i < mid; i++)
            q[order[i]] = 1;

        ll cost = ask(q);

        if (cost == total_cost) r = mid;
        else l = mid;
    }
    a = vt[l];

    r = (int)order.size();

    order.clear();
    vt.clear();

    dfs(a, a);

    l = 0, r = (int)order.size();

    while (r-l > 1) {
        int mid = (l+r)/2;

        vector<int> q(m, 0);
        for (int i = 0; i < mid; i++)
            q[order[i]] = 1;

        ll cost = ask(q);

        if (cost == total_cost) r = mid;
        else l = mid;
    }

    b = vt[l];

    answer(a, b);
}

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