Submission #915873

#	Time	Username	Problem	Language	Result	Execution time	Memory
915873		Matjaz	Teleporters (IOI08_teleporters)	C++14	100 / 100	991 ms	65536 KiB

teleporters

//
//  IOI2008Teleporters.cpp
//  
//
//  Created by Matjaz Leonardis on 24/01/2024.
//

#include <iostream>
#include <vector>
#include <algorithm>
#include <assert.h>

using namespace std;

int N,M;

int main(){
    cin >> N >> M;
    vector<pair<int,int> > X;
    vector<int> next(4*N, -1);
    
    for (int i=0;i<N;i++){
        int W,E;
        cin >> W >> E;
        
        X.push_back(make_pair(W, 4 * i));
        X.push_back(make_pair(W, 4 * i + 1));
        X.push_back(make_pair(E, 4 * i + 2));
        X.push_back(make_pair(E, 4 * i + 3));
        next[4 * i] = 4 * i + 3;
        next[4 * i + 2] = 4 * i + 1;
    }
    
    sort(X.begin(), X.end());
    for (int i=0;i<X.size() - 1; i++){
        //cout << i << " " << X[i].first << " " << X[i].second  << endl;
        if (next[X[i].second] == -1) next[X[i].second] = X[i + 1].second;
    }
    
    
    int jumps = 0;
    vector<int> cycle;
    vector<bool> visited(4 * N, false);
    
    
    for (int i=0;i<X.size();i++){
        //cout << next[X[i].second] << endl;
        //cout << i << " " << X[i].first << " " << X[i].second  << endl;
        if (visited[X[i].second]) continue;
        
        int current = X[i].second;
        int l = 0;
        visited[X[i].second] = true;
        
        //cout << current << " ";
        
        while (next[current] != X[i].second && next[current] != -1){
            l++;
            current = next[current];
            visited[current] = true;
            //cout << current << " ";
        }
        //cout << endl;
        
        assert(l % 2 == 1);
        
        //cout << "l:" << l << endl;

        if (i == 0){
            jumps += (l + 1) / 2;
        } else cycle.push_back(l);
    }
    
    sort(cycle.rbegin(), cycle.rend());
    for (int i=0;i<M;i++){
        if (i >= cycle.size()) break; else
        jumps += (cycle[i] + 1) / 2 + 2;
        //if (i < cycle.size()) cout << cycle[i] << endl;
    }
    if (M > cycle.size()){
        M -= cycle.size();
        if (M % 2 == 0) jumps += 2 * M;
        if (M % 2 == 1) jumps += 2 * M - 1;
        
    }
    
    
    cout << jumps << endl;
    
    
    return 0;
}

Compilation message (stderr)

teleporters.cpp: In function 'int main()':
teleporters.cpp:35:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   35 |     for (int i=0;i<X.size() - 1; i++){
      |                  ~^~~~~~~~~~~~~
teleporters.cpp:46:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   46 |     for (int i=0;i<X.size();i++){
      |                  ~^~~~~~~~~
teleporters.cpp:76:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   76 |         if (i >= cycle.size()) break; else
      |             ~~^~~~~~~~~~~~~~~
teleporters.cpp:80:11: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   80 |     if (M > cycle.size()){
      |         ~~^~~~~~~~~~~~~~

• Subtask 1: 5 / 5
• Subtask 2: 5 / 5
• Subtask 3: 5 / 5
• Subtask 4: 5 / 5
• Subtask 5: 5 / 5
• Subtask 6: 5 / 5
• Subtask 7: 5 / 5
• Subtask 8: 5 / 5
• Subtask 9: 5 / 5
• Subtask 10: 5 / 5
• Subtask 11: 5 / 5
• Subtask 12: 5 / 5
• Subtask 13: 5 / 5
• Subtask 14: 5 / 5
• Subtask 15: 5 / 5
• Subtask 16: 5 / 5
• Subtask 17: 5 / 5
• Subtask 18: 5 / 5
• Subtask 19: 5 / 5
• Subtask 20: 5 / 5