Submission #1030328

#	Time	Username	Problem	Language	Result	Execution time	Memory
1030328		Agreb	Longest Trip (IOI23_longesttrip)	C++17	85 / 100	20 ms	700 KiB

longesttrip

#include <bits/stdc++.h>
#include "longesttrip.h"
using namespace std;

int binary_search(vector <int> & path, int v){
    int l = -1, r = (int)path.size()-1;
    while (r-l > 1){
        int m = (l + r) / 2;
        vector <int> cur(m+1);
        for (int i = 0; i <= m; i++) cur[i] = path[i];
        if (are_connected(cur, {v})) r = m;
        else l = m;
    }
    return r;
}

vector <int> longest_trip(int N, int D){
    vector <int> path, clique, used(N);
    for (int i = 0; i <= 2; i++){
        for (int j = 0; j < i; j++){
            if (are_connected({i}, {j})){
                path = {i, j};
                used[i] = used[j] = 1;
                break;
            }
        }
        if (!path.empty()) break;
    }

    vector <int> non_edge;
    mt19937 rnd(239);
    for (int v = 0; v < N; v++){
        if (used[v]) continue;

        if (rnd() % 2) reverse(path.begin(), path.end());
        int P = path.size();
        int C = clique.size();
        int st = path[0], fin = path[P-1];

        // cout << v << endl;
        // for (int x : path) cout << x << " ";
        // cout << endl;
        // for (int y : clique) cout << y << endl;
        // cout << endl;

        if (!clique.empty()){
            int cp, cc;
            if (rnd() % 2){
                cp = are_connected(path, {v});
                cc = (cp == 0 ? 1 : are_connected(clique, {v}));
            }
            else{
                cc = are_connected(clique, {v});
                cp = (cc == 0 ? 1 : are_connected(path, {v}));
            }
            if (cp && cc){
                non_edge = {clique[0], path[0]};

                int ip = binary_search(path, v);
                int ic = binary_search(clique, v);

                vector <int> npath;
                for (int j = 0; j < P; j++) npath.push_back(path[(j+ip+1)%P]);
                npath.push_back(v);
                for (int j = 0; j < C; j++) npath.push_back(clique[(j+ic)%C]);
                path = npath;
                clique.clear();
                continue;
            }
            else if (cc){
                clique.push_back(v);
                continue;
            }
            else if (cp){
                path.push_back(v);
                continue;
            }
        }

        if (!non_edge.empty()){
            if (are_connected({st}, {v})){
                reverse(path.begin(), path.end());
                path.push_back(v);
                continue;
            }
            else if (are_connected({fin}, {v})){
                path.push_back(v);
                continue;
            }
            else{
                int u = (are_connected({non_edge[0]}, {v}) ? non_edge[0] : non_edge[1]); 
                int i = -1;
                for (int ii = 0; ii < P; ii++)
                    if (path[ii] == u) i = ii;
                             
                vector <int> npath;
                for (int j = 0; j < P; j++) 
                    npath.push_back(path[(j+i+1)%P]);
                npath.push_back(v);
                path = npath;
                continue;
            }
        }

        if (are_connected({st}, {v})){
            reverse(path.begin(), path.end());
            path.push_back(v);
            continue;
        }

        if (!are_connected(path, {v})){
            clique.push_back(v);
            continue;
        }

        if (non_edge.empty()) non_edge = {st, v};   
        
        if (are_connected({fin}, {v})){
            path.push_back(v);
            continue;
        }     

        int i = binary_search(path, v);
        vector <int> npath;
        for (int j = 0; j < P; j++) 
            npath.push_back(path[(j+i+1)%P]);
        npath.push_back(v);
        path = npath;
    }
    assert(path.size() + clique.size() == N);
    if (path.size() >= clique.size()) return path;
    else return clique;
}

Compilation message (stderr)

In file included from /usr/include/c++/10/cassert:44,
                 from /usr/include/x86_64-linux-gnu/c++/10/bits/stdc++.h:33,
                 from longesttrip.cpp:1:
longesttrip.cpp: In function 'std::vector<int> longest_trip(int, int)':
longesttrip.cpp:130:40: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
  130 |     assert(path.size() + clique.size() == N);
      |            ~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~

• Subtask 0: 0 / 0
• Subtask 1: 5 / 5
• Subtask 2: 10 / 10
• Subtask 3: 25 / 25
• Subtask 4: 45 / 60