Submission #155665

#	Time	Username	Problem	Language	Result	Execution time	Memory
155665		rama_pang	통행료 (IOI18_highway)	C++14	5 / 100	397 ms	262148 KiB

highway

#include "highway.h"
#include <bits/stdc++.h>
using namespace std;
using lint = long long;
const lint MAXN = 150005;

lint N, M, A, B;
vector<int> G[MAXN];
lint dist[MAXN];
struct edge {
    int u, v, id;
    edge(int uu, int vv, int idd): u(uu), v(vv), id(idd) { }
    bool operator < (const edge &o) {
        return dist[v] < dist[o.v];
    }
};

vector<edge> E;

void dfs(int n, int p, int d) {
    dist[n] = d;
    for (auto &i : G[n]) if (i != p) {
        dfs(i, n, d + 1);
    }
}

void find_pair(int _N, vector<int> U, vector<int> V, int _A, int _B) {
    N = _N, A = _A, B = _B, M = U.size();
    for (int i = 0; i < M; i++) {
        G[U[i]].emplace_back(V[i]);
        G[V[i]].emplace_back(U[i]);
        E.emplace_back(U[i], V[i], i);
    }
    dfs(0, -1, 0);
    for (int i = 0; i < M; i++) {
        if (dist[E[i].u] > dist[E[i].v]) swap(E[i].u, E[i].v);
    }
    sort(E.begin(), E.end());
    lint le = 0, ri = M - 1;
    lint ans = (dist[E.back().u] > dist[E.back().v])? E.back().u : E.back().v;
    vector<int> guess(M, 0);
    lint D = ask(guess) / A;
    while (le <= ri) {
        guess.assign(M, 0);
        lint mid = (le + ri) / 2;
        for (int i = 0; i <= mid; i++) guess[E[i].id] = 1;
        int check = ask(guess);
        // cout << le << " " << ri << " " << check << "\n";
        if (check == D * B) {
            ans = mid;
            ri = mid - 1;
        } else {
            // ans = mid;
            le = mid + 1;
        }
    }
    // cout << ans << "\n";
    ans = (dist[E[ans].u] == D)? E[ans].u : E[ans].v;
    answer(0, ans);
}

/*

4 4 1 3 1 3
0 1
0 2
0 3
1 2

4 3 1 3 0 1
0 1
0 2
0 3

4 3 1 3 0 1
0 1
0 3
1 2


*/

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