Submission #915601

#	Time	Username	Problem	Language	Result	Execution time	Memory
915601		Matjaz	Teleporters (IOI08_teleporters)	C++14	10 / 100	222 ms	65536 KiB

teleporters

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

#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

int N,M;

int main(){
    cin >> N >> M;
    vector<pair<int,int> > X(4*N);
    vector<int> next(4*N, -1);
    
    for (int i=0;i<N;i++){
        int 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++){
        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++){
        if (visited[X[i].second]) continue;
        
        int current = X[i].second;
        int l = 0;
        visited[X[i].second] = true;
        
        while (next[current] != X[i].second && next[current] != -1){
            l++;
            current = next[current];
            visited[current] = true;
        }

        if (i == 0){
            jumps += l;
        } else cycle.push_back(l);
    }
    
    sort(cycle.rbegin(), cycle.rend());
    for (int i=0;i<M;i++){
        if (i >= cycle.size()) jumps += 4; else
        jumps += cycle[i] + 2;
    }
    
    cout << jumps << endl;
    
    
    return 0;
}

Compilation message (stderr)

teleporters.cpp: In function 'int main()':
teleporters.cpp:33:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   33 |     for (int i=0;i<X.size() - 1; i++){
      |                  ~^~~~~~~~~~~~~
teleporters.cpp:43:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   43 |     for (int i=0;i<X.size();i++){
      |                  ~^~~~~~~~~
teleporters.cpp:63:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   63 |         if (i >= cycle.size()) jumps += 4; else
      |             ~~^~~~~~~~~~~~~~~
teleporters.cpp:24:39: warning: 'W' may be used uninitialized in this function [-Wmaybe-uninitialized]
   24 |         X.push_back(make_pair(W, 4 * i));
      |                                       ^
teleporters.cpp:26:43: warning: 'E' may be used uninitialized in this function [-Wmaybe-uninitialized]
   26 |         X.push_back(make_pair(E, 4 * i + 2));
      |                                           ^

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