Submission #281986

#	Time	Username	Problem	Language	Result	Execution time	Memory
281986		A02	Shortcut (IOI16_shortcut)	C++14	23 / 100	2083 ms	504 KiB

shortcut

#include "shortcut.h"
#include <vector>
#include <iostream>
#include <set>
#include <algorithm>
#include <utility>
#include <queue>

using namespace std;

long long find_shortcut(int n, std::vector<int> l, std::vector<int> d, int c)
{
    long long BIG = (long long) 1 << 62;

    long long best = BIG;

    vector<vector<pair<int, long long> > > adjacent (n, vector<pair<int, long long> > ());

    for (int i = 0; i < n - 1; i++){

        adjacent[i].push_back(make_pair(i + 1, l[i]));
        adjacent[i + 1].push_back(make_pair(i, l[i]));

    }

    for (int s = 0; s < n; s++){
        for (int e = s + 1; e < n; e++){

            //Express line between s and e.

            //Longest path in [0, s].

            long long diameter = 0;
//
//            long long b1 = d[0];
//            long long b1_partial = d[0];
//
//            for (int i = 1; i <= s; i++){
//                b1_partial += l[i - 1];
//                b1 = max(b1_partial + d[i], b1);
//                b1_partial = max(b1_partial, d[i]);
//            }
//
//            diameter = max(diameter, b1);
//
//            long long bn = d[n - 1];
//            long long bn_partial = d[n - 1];
//
//            for (int i = n - 1; i >= e; i--){
//                bn_partial += l[i - 1];
//                bn = max(bn_partial + d[i], bn);
//                bn_partial = max(bn_partial, d[i]);
//            }
//
//            diameter = max(diameter, bn);
//
//            long long bs = 0;
//
            if (e != s + 1){
                adjacent[s].push_back(make_pair(e, c));
                adjacent[e].push_back(make_pair(s, c));
            } else {
                    adjacent[s].pop_back();
                    adjacent[e].pop_back();

                    if (s > 0){
                        adjacent[s].pop_back();
                        adjacent[s].push_back(make_pair(s - 1, l[s - 1]));
                    }
                    if (e < n - 1){
                        adjacent[e].pop_back();
                        adjacent[e].push_back(make_pair(e + 1, l[e]));
                    }

                    adjacent[s].push_back(make_pair(e, min(l[s], c)));
                    adjacent[e].push_back(make_pair(s, min(l[s], c)));
            }

            for (int a = 0; a < n; a++){

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

                vector<long long> visited (n, -1);

                to_visit.push(make_pair(-d[a], a));
                visited[a] = -1;
                diameter = max(diameter, (long long) d[a]);

                while (!to_visit.empty()){

                    pair<long long, int> current_p = to_visit.top();
                    int current = current_p.second;
                    to_visit.pop();

                    if (visited[current] == -1){

                        visited[current] = -current_p.first;
                        //cout << s<< ' ' << e << ' ' <<  a << ' ' << current << ' ' << visited[current] << ' ' << d[current]<< endl;
                        if (current != a){
                            diameter = max(diameter, visited[current] + d[current]);
                        }

                        for (int i = 0; i < adjacent[current].size(); i++){
                            int next = adjacent[current][i].first;
                            //cout << 'n' << next << endl;
                            if (visited[next] == -1){
                                pair<long long, int> n;
                                n.first = -visited[current] - adjacent[current][i].second;
                                n.second = next;
                                to_visit.push(n);
                                //cout << endl << n.first << ' ' << n.second << endl;
                            }
                        }
                    }
                }

            }

            adjacent[s].pop_back();
            adjacent[e].pop_back();

            if (e == s + 1){
                adjacent[s].push_back(make_pair(e, l[s]));
                adjacent[e].push_back(make_pair(s, l[s]));
            }
            //cout << diameter << ' ' << endl << endl;
            best = min(best, diameter);
        }


    }


    return best;
}

Compilation message (stderr)

shortcut.cpp: In function 'long long int find_shortcut(int, std::vector<int>, std::vector<int>, int)':
shortcut.cpp:103:43: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, long long int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  103 |                         for (int i = 0; i < adjacent[current].size(); i++){
      |                                         ~~^~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 9 / 9
• Subtask 2: 14 / 14
• Subtask 3: 0 / 8
• Subtask 4: 0 / 7
• Subtask 5: 0 / 33
• Subtask 6: 0 / 22
• Subtask 7: 0 / 4
• Subtask 8: 0 / 3