Submission #851527

#	Time	Username	Problem	Language	Result	Execution time	Memory
851527		batmendbar	Longest Trip (IOI23_longesttrip)	C++17	100 / 100	15 ms	852 KiB

longesttrip

#include "longesttrip.h"
#include <algorithm>
#include <random>
#include <stack>
#include <iostream>

using namespace std;

vector<int> longest_trip(int N, int D)
{
    vector<int> big, small, nodes;

    for (int i = 0; i < N; i++) 
        nodes.push_back(i);

    random_device rd;
    mt19937 g(rd());
    shuffle(nodes.begin(), nodes.end(), g);
    
    // for (int node : nodes) cout << node << ' ';
    // cout << '\n';
    // cout.flush();

    big.push_back(nodes[0]);
    small.push_back(nodes[1]);
    
    bool guarantee = false;

    for (int i = 2; i < N; i++) {
        if (are_connected(vector<int>{big.back()}, vector<int>{nodes[i]})) {
            big.push_back(nodes[i]);
            guarantee = false;
        } else if (guarantee) {
            small.push_back(nodes[i]);
        } else if (are_connected(vector<int>{small.back()}, vector<int>{nodes[i]})) {
            small.push_back(nodes[i]);
            guarantee = true;
        } else {
            if (small.size() == 1) guarantee = true;
            while (!small.empty()) {
                big.push_back(small.back());
                small.pop_back();
            }
            small.push_back(nodes[i]);
        }
    }

    // cout << "Big: ";
    // for (int i : big) cout << i << ' ';
    // cout << '\n';


    // cout << "Small: ";
    // for (int i : small) cout << i << ' ';
    // cout << '\n';

    // cout.flush();
    // return nodes;

    if (are_connected(big, small)) {
        if (are_connected(vector<int>{big.back()}, vector<int>{small.back()})) {
            big.insert(big.end(), small.rbegin(), small.rend());
            return big;
        }

        if (are_connected(vector<int>{big[0]}, vector<int>{small[0]})) {
            reverse(small.begin(), small.end());
            small.insert(small.end(), big.begin(), big.end());
            return small;
        } 
        if (are_connected(vector<int>{big.back()}, vector<int>{small[0]})) {
            big.insert(big.end(), small.begin(), small.end());
            return big;
        }
        if (are_connected(vector<int>{big[0]}, vector<int>{small.back()})) {
            small.insert(small.end(), big.begin(), big.end());
            return small;
        } 
        
        int l = 0, r = big.size() - 1;
        while (l < r) {
            int mid = (l + r) / 2;
            std::vector<int>::iterator begin = big.begin() + l; // Start from index 1
            std::vector<int>::iterator end = big.begin() + mid + 1;
            vector<int> tempBig(begin, end);
            if (are_connected(small, tempBig)) {
                r = mid;
            } else {
                l = mid + 1;
            }
        }
        int bigInd = l;

        l = 0, r = small.size() - 1;
        while (l < r) {
            int mid = (l + r) / 2;
            std::vector<int>::iterator begin = small.begin() + l; // Start from index 1
            std::vector<int>::iterator end = small.begin() + mid + 1;
            vector<int> tempSmall(begin, end);
            if (are_connected(tempSmall, vector<int>{big[bigInd]})) {
                r = mid;
            } else {
                l = mid + 1;
            }
        }
        int smallInd = l;
        // cout << "Indices: " << bigInd << ' ' << smallInd << '\n';
        // cout.flush();
        vector<int> ans;
        
        for (int i = smallInd + 1; i < small.size(); i++) {
            ans.push_back(small[i]);
        }
        for (int i = 0; i <= smallInd; i++) {
            ans.push_back(small[i]);
        }
        for (int i = bigInd; i < big.size(); i++) {
            ans.push_back(big[i]);
        }
        for (int i = 0; i < bigInd; i++) {
            ans.push_back(big[i]);
        }
        return ans;
    } else {
        if (big.size() < small.size()) return small;
        else return big;    
    }
}

Compilation message (stderr)

longesttrip.cpp: In function 'std::vector<int> longest_trip(int, int)':
longesttrip.cpp:111:38: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  111 |         for (int i = smallInd + 1; i < small.size(); i++) {
      |                                    ~~^~~~~~~~~~~~~~
longesttrip.cpp:117:32: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  117 |         for (int i = bigInd; i < big.size(); i++) {
      |                              ~~^~~~~~~~~~~~

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