Submission #561932

#	Time	Username	Problem	Language	Result	Execution time	Memory
561932		timreizin	Meetings (JOI19_meetings)	C++17	100 / 100	722 ms	848 KiB

meetings

#pragma GCC optimize("Ofast,unroll-loops")
#pragma GCC target("avx2,bmi,bmi2,popcnt,lzcnt")

#include "meetings.h"
#include <random>
#include <vector>
#include <set>
#include <numeric>
#include <algorithm>
#include <map>

using namespace std;

vector<vector<int>> adj;
mt19937 gen(989324);

void find(vector<int> &vertices)
{
    if (vertices.size() == 1) return;
    if (vertices.size() == 2)
    {
        adj[vertices.front()].push_back(vertices.back());
        adj[vertices.back()].push_back(vertices.front());
        return;
    }
    vector<int> path;
    map<int, vector<int>> comps;
    int x = uniform_int_distribution<>(0, (int)vertices.size() - 1)(gen);
    int y = x;
    while (y == x) y = uniform_int_distribution<>(0, (int)vertices.size() - 1)(gen);
    x = vertices[x];
    y = vertices[y];
    path.push_back(x);
    for (int i = 0; i < vertices.size(); ++i)
    {
        if (x == vertices[i] || y == vertices[i]) continue;
        int r = Query(x, y, vertices[i]);
        if (r != vertices[i]) comps[r].push_back(vertices[i]);
        else path.push_back(r);
    }
    for (auto &[pivot, vertices] : comps)
    {
        vertices.push_back(pivot);
        find(vertices);
    }
    sort(path.begin() + 1, path.end(), [&x](int a, int b) { return Query(x, a, b) == a; });
    path.push_back(y);
    for (int i = 0; i + 1 < path.size(); ++i)
    {
        adj[path[i]].push_back(path[i + 1]);
        adj[path[i + 1]].push_back(path[i]);
    }
}

void Solve(int n)
{
    adj.resize(n);
    set<int> path;
    vector<int> vertices(n);
    iota(vertices.begin(), vertices.end(), 0);
    find(vertices);
    for (int i = 0; i < n; ++i) for (int u : adj[i]) if (i < u) Bridge(i, u);
}

Compilation message (stderr)

meetings.cpp: In function 'void find(std::vector<int>&)':
meetings.cpp:34:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   34 |     for (int i = 0; i < vertices.size(); ++i)
      |                     ~~^~~~~~~~~~~~~~~~~
meetings.cpp:48:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   48 |     for (int i = 0; i + 1 < path.size(); ++i)
      |                     ~~~~~~^~~~~~~~~~~~~

• Subtask 1: 7 / 7
• Subtask 2: 10 / 10
• Subtask 3: 12 / 12
• Subtask 4: 71 / 71