Submission #864315

#	Time	Username	Problem	Language	Result	Execution time	Memory
864315		raphaelp	Sightseeing (NOI14_sightseeing)	C++14	15 / 25	3954 ms	262144 KiB

sightseeing

#include <bits/stdc++.h>
using namespace std;
class UnionFind
{
private:
    vector<int> p, rank;
    int numSets;

public:
    UnionFind(int m)
    {
        p.assign(m, 0);
        for (int i = 0; i < m; ++i)
            p[i] = i;
        rank.assign(m, 0);
        numSets = m;
    }
    int find(int x) { return (p[x] == x) ? x : p[x] = find(p[x]); }
    bool sameSet(int a, int b) { return find(a) == find(b); }
    int nbSets() { return numSets; }
    bool merge(int a, int b)
    {
        if (sameSet(a, b))
            return false;
        int x = find(a);
        int y = find(b);
        if (rank[x] > rank[y])
            swap(x, y);
        p[x] = y;
        if (rank[x] == rank[y])
            rank[y]++;
        numSets--;
        return true;
    }
};
void par(int n, int p, vector<vector<pair<int, int>>> &parent, vector<vector<pair<int, int>>> &roads, vector<int> &prof)
{
    parent[n][0].first = p;
    prof[n] = prof[p] + 1;
    for (int i = 0; i < roads[n].size(); i++)
    {
        if (roads[n][i].first == p)
            continue;
        parent[roads[n][i].first][0].second = roads[n][i].second;
        par(roads[n][i].first, n, parent, roads, prof);
    }
}
void linsort(vector<tuple<int, int, int>> &aretes)
{
    vector<vector<tuple<int, int, int>>> Temp(100010, vector<tuple<int, int, int>>(0));
    for (int i = 0; i < aretes.size(); i++)
    {
        Temp[get<0>(aretes[i])].push_back(aretes[i]);
    }
    aretes.clear();
    for (int i = 0; i < 100010; i++)
    {
        for (int j = 0; j < Temp[i].size(); j++)
        {
            aretes.push_back(Temp[i][j]);
        }
    }
}
int main()
{
    int N, M, q;
    cin >> N >> M >> q;
    vector<vector<pair<int, int>>> roads(N, vector<pair<int, int>>(0));
    vector<tuple<int, int, int>> aretes(M);
    for (int i = 0; i < M; i++)
    {
        int a, b, c;
        cin >> a >> b >> c;
        aretes[i] = {c, b - 1, a - 1};
    }
    vector<vector<pair<int, int>>> parent(N, vector<pair<int, int>>(20, {0, 123456789}));
    linsort(aretes);
    UnionFind UF(N);
    for (int i = aretes.size() - 1; UF.nbSets() > 1; i--)
    {
        if (UF.merge(get<1>(aretes[i]), get<2>(aretes[i])))
        {
            roads[get<1>(aretes[i])].push_back({get<2>(aretes[i]), get<0>(aretes[i])});
            roads[get<2>(aretes[i])].push_back({get<1>(aretes[i]), get<0>(aretes[i])});
        }
    }
    vector<int> prof(N, 0);
    par(0, 0, parent, roads, prof);
    for (int i = 1; i < 20; i++)
    {
        for (int j = 0; j < N; j++)
        {
            parent[j][i].first = parent[parent[j][i - 1].first][i - 1].first;
            parent[j][i].second = min(parent[parent[j][i - 1].first][i - 1].second, parent[j][i - 1].second);
        }
    }
    for (int j = 0; j < q; j++)
    {
        int a = 1, b;
        cin >> b;
        a--;
        b--;
        if (prof[a] < prof[b])
            swap(a, b);
        int minn = 123456789;
        for (int i = 19; i >= 0; i--)
        {
            if (prof[a] - (1 << i) >= prof[b])
            {
                minn = min(minn, parent[a][i].second);
                a = parent[a][i].first;
            }
        }
        if (a != b)
        {
            for (int i = 19; i >= 0; i--)
            {
                if (parent[a][i].first != parent[b][i].first)
                {
                    minn = min(minn, parent[a][i].second);
                    minn = min(minn, parent[b][i].second);
                    a = parent[a][i].first;
                    b = parent[b][i].first;
                }
            }
            minn = min(minn, parent[a][0].second);
            minn = min(minn, parent[b][0].second);
        }

        cout << minn << '\n';
    }
}

Compilation message (stderr)

sightseeing.cpp: In function 'void par(int, int, std::vector<std::vector<std::pair<int, int> > >&, std::vector<std::vector<std::pair<int, int> > >&, std::vector<int>&)':
sightseeing.cpp:40:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   40 |     for (int i = 0; i < roads[n].size(); i++)
      |                     ~~^~~~~~~~~~~~~~~~~
sightseeing.cpp: In function 'void linsort(std::vector<std::tuple<int, int, int> >&)':
sightseeing.cpp:51:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::tuple<int, int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   51 |     for (int i = 0; i < aretes.size(); i++)
      |                     ~~^~~~~~~~~~~~~~~
sightseeing.cpp:58:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::tuple<int, int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   58 |         for (int j = 0; j < Temp[i].size(); j++)
      |                         ~~^~~~~~~~~~~~~~~~

• Subtask 1: 4 / 4
• Subtask 2: 5 / 5
• Subtask 3: 6 / 6
• Subtask 4: 0 / 10