Submission #920873

#	Time	Username	Problem	Language	Result	Execution time	Memory
920873		simuyu	Monthly railway pass (LMIO18_menesinis_bilietas)	C++14	6 / 100	733 ms	83340 KiB

menesinis_bilietas

#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define f first
#define s second

vector<set<long> > adjs; // note that will have to findSet each of these.

class UFDS
{
    public:
    vector<long> parent, sizes;
    long num_sets;
    UFDS(long n) {
        for (long i=0; i<n; i++) {
            parent.push_back(i);
        }
        for (long i=0; i<n; i++) {
            sizes.push_back(1);
        }
        num_sets = n;
    }

    long findSet(long i) {
        if (parent[i] == i) return i;
        vector<long> elems; // path compression
        while (parent[i] != i) {
            elems.push_back(i);
            i = parent[i];
        }
        for (long idx=0; idx<elems.size(); idx++) {
            parent[elems[i]] = i;
        }
        return i;
    }

    void unionSets(long i, long j) {
        //cout << "UNION " << i << ' ' << j << ": ";
        i = findSet(i);
        j = findSet(j);
        //cout << i << ' ' << j << "; ";
        if (i==j) return;
        if (sizes[i] < sizes[j]) swap(i, j); // so i >= j in size, not rlly depth but.
        parent[j] = i; // set parent
        //cout << sizes[i] << ' ' << sizes[j] << ": ";
        sizes[i] += sizes[j]; // update size
        //cout << sizes[i] << ' ' << sizes[j] << "; ";
        // union the adjs
        for (auto it = adjs[j].begin(); it != adjs[j].end(); it++) {
            adjs[i].insert(*it);
        }
        adjs[j].clear();

        // update number of sets
        num_sets --;

        // done :)
    }

    //long getSize(long s) return sizes[s];
};

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);

    //  modifier ufds
    // store unordered set of neighbours of each edge and when union, combine them.
    long n, m;
    cin >> n >> m;

    for (long idx=0; idx<n; idx++) adjs.push_back(set<long>());

    long i, j;
    char t;
    UFDS ufds(n);

    for (long idx=0; idx<m; idx++) {
        cin >> i >> j >> t;
        if (t=='A') {
            // add to adjs
            i = ufds.findSet(i-1);
            j = ufds.findSet(j-1);
            adjs[i].insert(j);
            adjs[j].insert(i);
        } else {
            // union the sets
            ufds.unionSets(i-1, j-1);
        }
    }

    // ufds done:)
    // check.
    /*cout << "UFDS DEBUG: \n";

    cout << "PARENT: ";
    for (long i=0; i<n; i++) cout << ufds.parent[i] << ' ';
    cout << endl;

    cout << "SIZE: ";
    for (long i=0; i<n; i++) cout << ufds.sizes[i] << ' ';
    cout << endl;

    cout << "ADJ: " << endl;
    for (long i=0; i<n; i++) {
        cout << i << ": ";
        for (auto it=adjs[i].begin(); it!=adjs[i].end(); it++) {
            cout << *it << ' ' ;
        }
        cout << endl;
    }
    cout << endl << endl;*/


    // get size of each component's adjs (rmbring to remove duplicates)
    long res=0;
    set<long> s;
    for (long i=0; i<n; i++) {

        //cout << i << ": ";

        for (auto it=adjs[i].begin(); it!=adjs[i].end(); it++) {
            s.insert(ufds.findSet(*it)); // add
            //cout << ufds.findSet(*it) << ' ';
        }

        //cout << endl;


        if (s.size() == ufds.num_sets-1) {
            //cout << "COUNTED: " << i << endl;
            res += ufds.sizes[i];
        }
        s.clear(); // :)
    }


    cout << res << '\n';

    return 0;
}

Compilation message (stderr)

menesinis_bilietas.cpp: In member function 'long int UFDS::findSet(long int)':
menesinis_bilietas.cpp:31:29: warning: comparison of integer expressions of different signedness: 'long int' and 'std::vector<long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   31 |         for (long idx=0; idx<elems.size(); idx++) {
      |                          ~~~^~~~~~~~~~~~~
menesinis_bilietas.cpp: In function 'int main()':
menesinis_bilietas.cpp:131:22: warning: comparison of integer expressions of different signedness: 'std::set<long int>::size_type' {aka 'long unsigned int'} and 'long int' [-Wsign-compare]
  131 |         if (s.size() == ufds.num_sets-1) {
      |                      ^

• Subtask 1: 0 / 10
• Subtask 2: 6 / 6
• Subtask 3: 0 / 30
• Subtask 4: 0 / 35
• Subtask 5: 0 / 19