Submission #611758

#	Time	Username	Problem	Language	Result	Execution time	Memory
611758		Jomnoi	Highway Tolls (IOI18_highway)	C++17	12 / 100	144 ms	9032 KiB

highway

#include <bits/stdc++.h>
#include "highway.h"
using namespace std;

// subtask 1, 2

const int MAX_N = 9e4 + 5;

long long result;
vector <int> U, V, W;
vector <int> graph[MAX_N];
vector <int> canbeanswer;
int holdedge[MAX_N];

void dfs(int u, int p, int depth) {
    if(depth == 0) {
        canbeanswer.push_back(u);
        return;
    }
    for(auto i : graph[u]) {
        int v = u ^ U[i] ^ V[i];
        if(v != p) {
            holdedge[v] = i;
            dfs(v, u, depth - 1);
        }
    }
}

void find_pair(int N, vector <int> u, vector <int> v, int A, int B) {
    int M = u.size();
    U.resize(M);
    V.resize(M);
    W.resize(M, 0);
    for(int i = 0; i < M; i++) {
        U[i] = u[i], V[i] = v[i];
        graph[U[i]].push_back(i);
        graph[V[i]].push_back(i);
    }

    result = ask(W);

    int numberofEdge = result / A;

    dfs(0, -1, numberofEdge);

    int l = 0, r = canbeanswer.size() - 1, pos = 0;
    while(l <= r) {
        int mid = (l + r) / 2;

        W.clear();
        W.resize(M, 0);
        for(int i = 0; i <= mid; i++) {
            W[holdedge[canbeanswer[i]]] = 1;
        }

        result = ask(W);
        if(result == 1ll*numberofEdge * A) {
            l = mid + 1;
        }
        else {
            r = mid - 1;
            pos = mid;
        }
    }
    answer(0, canbeanswer[pos]);
}

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