Submission #893971

#	Time	Username	Problem	Language	Result	Execution time	Memory
893971		borisAngelov	Evacuation plan (IZhO18_plan)	C++17	41 / 100	4054 ms	37160 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];

vector<long long> toTry;

struct Query
{
    int from;
    int to;
    int idx;

    Query()
    {

    }

    Query(int _from, int _to, int _idx)
    {
        from = _from;
        to = _to;
        idx = _idx;
    }
};

struct roll_back
{
    long long a;
    long long b;
    long long rnka,rnkb;
    long long where;
};
stack <roll_back> s;

long long par[maxn],rnk[maxn];

void roll_back(long long pos)
{
    while(!s.empty() && s.top().where<=pos)
    {
        auto t = s.top();
        s.pop();
        rnk[t.a] = t.rnka;
        rnk[t.b] = t.rnkb;
        par[t.a] = t.a;
        par[t.b] = t.b;
    }
}
long long Find(long long p)
{
    if(par[p]==p)
        return p;
    return Find(par[p]);
}
void Union(long long p,long long q,long long where)
{
  //  cout<<"Union "<<p<<" "<<q<<" "<<where<<endl;
    long long parp,parq;
    p = Find(p);
    q = Find(q);
    if(p==q)return ;
    //cout<<"svurzvame "<<p<<" "<<q<<endl;
    s.push({p,q,rnk[p],rnk[q],where});
    if(rnk[p]<rnk[q])swap(p,q);
    if(rnk[p]==rnk[q])
        rnk[p]++;
    par[q] = p;
}

vector<Query> queries;
long long answers[maxn];

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

void parallelBinarySearch(int level, int l, int r, vector<int>& curr)
{
    if (l > r)
    {
        return;
    }

    if (curr.empty())
    {
        return;
    }

    if (l == r)
    {
        for (int i = 0; i < curr.size(); ++i)
        {
            answers[queries[curr[i]].idx] = toTry[l];
        }

        return;
    }

    int mid = (l + r) / 2;

    for (int i = toTry.size() - 1; i >= mid; --i)
    {
        for (int j = 0; j < byValue[i].size(); ++j)
        {
            Union(byValue[i][j].first, byValue[i][j].second, i);
        }
    }

    roll_back(mid);

    vector<int> toLeft;
    vector<int> toRight;

    for (int i = 0; i < curr.size(); ++i)
    {
        if (Find(queries[curr[i]].from) == Find(queries[curr[i]].to))
        {
            toRight.push_back(curr[i]);
        }
        else
        {
            toLeft.push_back(curr[i]);
        }
    }

    parallelBinarySearch(level + 1, l, mid, toLeft);
    parallelBinarySearch(level + 1, mid + 1, r, toRight);
}

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

    for (int i = 1; i <= n; ++i)
    {
        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)
            {
                long long d = min(dist[i], dist[g[i][j].first]);

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

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

                    if (toTry[mid] >= d)
                    {
                        r = mid - 1;
                    }
                    else
                    {
                        l = mid + 1;
                    }
                }

                byValue[l].push_back(make_pair(i, g[i][j].first));
            }
        }
    }

    cin >> q;

    for (int i = 1; i <= q; ++i)
    {
        int from, to;
        cin >> from >> to;
        queries.push_back(Query(from, to, i));
    }

    for(int i=1;i<=n;i++)
        par[i] = i,rnk[i] = 1;

    vector<int> starting;

    for (int i = 0; i < q; ++i)
    {
        starting.push_back(i);
    }

    parallelBinarySearch(1, 0, toTry.size() - 1, starting);

    for (int i = 1; i <= q; ++i)
    {
        cout << answers[i] << "\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
*/

Compilation message (stderr)

plan.cpp: In function 'void Union(long long int, long long int, long long int)':
plan.cpp:69:15: warning: unused variable 'parp' [-Wunused-variable]
   69 |     long long parp,parq;
      |               ^~~~
plan.cpp:69:20: warning: unused variable 'parq' [-Wunused-variable]
   69 |     long long parp,parq;
      |                    ^~~~
plan.cpp: In function 'void parallelBinarySearch(int, int, int, std::vector<int>&)':
plan.cpp:100:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  100 |         for (int i = 0; i < curr.size(); ++i)
      |                         ~~^~~~~~~~~~~~~
plan.cpp:112:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  112 |         for (int j = 0; j < byValue[i].size(); ++j)
      |                         ~~^~~~~~~~~~~~~~~~~~~
plan.cpp:123:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  123 |     for (int i = 0; i < curr.size(); ++i)
      |                     ~~^~~~~~~~~~~~~
plan.cpp: In function 'int main()':
plan.cpp:205:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  205 |         for (int i = 0; i < g[node].size(); ++i)
      |                         ~~^~~~~~~~~~~~~~~~
plan.cpp:231:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  231 |         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