제출 #893896

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
893896		borisAngelov	Evacuation plan (IZhO18_plan)	C++17	41 / 100	4064 ms	30760 KiB

plan

#include <bits/stdc++.h>

using namespace std;

const int maxn = 100005;
const long long inf = (1LL << 61);

int n, m, k, q;

int startCities[maxn];

vector<pair<int, int>> g[maxn];

long long dist[maxn];

struct DSU
{
    int par[maxn];
    int dep[maxn];

    void init()
    {
        for (int i = 1; i <= n; ++i)
        {
            par[i] = i;
            dep[i] = 1;
        }
    }

    int root(int node)
    {
        if (node == par[node])
        {
            return node;
        }

        return par[node] = root(par[node]);
    }

    void connect(int x, int y)
    {
        x = root(x);
        y = root(y);

        if (x == y)
        {
            return;
        }

        if (dep[x] >= dep[y])
        {
            par[y] = x;

            if (dep[x] == dep[y])
            {
                ++dep[x];
            }
        }
        else
        {
            par[x] = y;
        }
    }

    bool areConnected(int x, int y)
    {
        return root(x) == root(y);
    }
};

DSU dsu;

vector<long long> toTry;

struct Edge
{
    int from;
    int to;
    long long w;

    Edge()
    {

    }

    Edge(int _from, int _to, long long _w)
    {
        from = _from;
        to = _to;
        w = _w;
    }

    bool operator < (const Edge& other) const
    {
        return w < other.w;
    }
};

vector<Edge> edges;

bool check(int from, int to, long long minW)
{
    //cout << "checking for " << minW << endl;
    dsu.init();

    int l = 0;
    int r = m - 1;

    while (l <= r)
    {
        int mid = (l + r) / 2;

        if (edges[mid].w >= minW)
        {
            r = mid - 1;
        }
        else
        {
            l = mid + 1;
        }
    }

    for (int i = l; i < m; ++i)
    {
        //cout << "add edge " << edges[i].from << ' ' << edges[i].to << ' ' << edges[i].w << endl;
        dsu.connect(edges[i].from, edges[i].to);
    }

    return dsu.areConnected(from, to);
}

long long solve(int from, int to)
{
    //cout << "query " << from << " " << to << endl;

    int l = 0;
    int r = toTry.size() - 1;

    while (l <= r)
    {
        int mid = (l + r) / 2;

        if (check(from, to, toTry[mid]) == true)
        {
            l = mid + 1;
        }
        else
        {
            r = mid - 1;
        }
    }

    return toTry[r];
}

vector<long long> uniqueDistances()
{
    set<long long> s;
    vector<long long> res;

    for (int i = 1; i <= n; ++i)
    {
        if (s.find(dist[i]) == s.end())
        {
            s.insert(dist[i]);
        }
    }

    for (auto element : s)
    {
        res.push_back(element);
    }

    return res;
}

void fastIO()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
}

int main()
{
    fastIO();

    cin >> n >> m;

    for (int i = 1; i <= m; ++i)
    {
        int x, y, w;
        cin >> x >> y >> w;

        g[x].push_back(make_pair(y, w));
        g[y].push_back(make_pair(x, w));
    }

    cin >> k;

    for (int i = 1; i <= k; ++i)
    {
        cin >> startCities[i];
    }

    for (int i = 1; i <= n; ++i)
    {
        dist[i] = inf;
    }

    priority_queue<pair<long long, int>> pq;

    for (int i = 1; i <= k; ++i)
    {
        pq.push(make_pair(0, startCities[i]));
        dist[startCities[i]] = 0;
    }

    while (!pq.empty())
    {
        int node = pq.top().second;
        long long curr = -pq.top().first;
        pq.pop();

        for (int i = 0; i < g[node].size(); ++i)
        {
            long long path = g[node][i].second + curr;
            int to = g[node][i].first;

            if (dist[to] > path)
            {
                dist[to] = path;
                pq.push(make_pair(-path, to));
            }
        }
    }

    /*cout << "check " << endl;

    for (int i = 1; i <= n; ++i)
    {
        cout << dist[i] << ' ';
    }

    cout << endl;*/

    toTry = uniqueDistances();

    for (int i = 1; i <= n; ++i)
    {
        for (int j = 0; j < g[i].size(); ++j)
        {
            if (i < g[i][j].first)
            {
                edges.push_back(Edge(i, g[i][j].first, min(dist[i], dist[g[i][j].first])));
            }
        }
    }

    sort(edges.begin(), edges.end());

    cin >> q;

    for (int i = 1; i <= q; ++i)
    {
        int from, to;
        cin >> from >> to;
        cout << solve(from, to) << "\n";
    }

    return 0;
}

/*
9 12
1 9 4
1 2 5
2 3 7
2 4 3
4 3 6
3 6 4
8 7 10
6 7 5
5 8 1
9 5 7
5 4 12
6 8 2
2
4 7
5
1 6
5 3
4 8
5 8
1 5
*/

컴파일 시 표준 에러 (stderr) 메시지

plan.cpp: In function 'int main()':
plan.cpp:225:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  225 |         for (int i = 0; i < g[node].size(); ++i)
      |                         ~~^~~~~~~~~~~~~~~~
plan.cpp:251:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  251 |         for (int j = 0; j < g[i].size(); ++j)
      |                         ~~^~~~~~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 0 / 13
• Subtask 3: 12 / 12
• Subtask 4: 19 / 19
• Subtask 5: 0 / 46