Submission #1081889

#	Time	Username	Problem	Language	Result	Execution time	Memory
1081889		ArthuroWich	Longest Trip (IOI23_longesttrip)	C++17	85 / 100	17 ms	856 KiB

longesttrip

#include "longesttrip.h"
#include<bits/stdc++.h>
using namespace std;
vector<int> longest_trip(int n, int d) {
    vector<int> a, b, ans, st;
    for (int i = 0; i < n; i++) {
        st.push_back(i);
    }
    random_device rd;
    mt19937 g(rd());
    shuffle(st.begin(), st.end(), g);
    a = {st[0]};
    b = {st[1]};
    st.erase(st.begin());
    st.erase(st.begin());
    set<pair<int, int>> ch;
    for (int i : st) {
        if (ch.count({min(a.back(), b.back()), max(a.back(), b.back())})) {
            if (are_connected({a.back()}, {i})) {
                a.push_back(i);
            } else {
                b.push_back(i);
                ch.insert({min(a.back(), b.back()), max(a.back(), b.back())});
            }
            continue;
        }
        if (are_connected({a.back(), b.back()}, {i})) {
            if (are_connected({a.back()}, {i})) {
                a.push_back(i);
            } else {
                b.push_back(i);
                ch.insert({min(a.back(), b.back()), max(a.back(), b.back())});
            }
        } else {
            if (b.size() == 1) {
                ch.insert({min(i, b.back()), max(i, b.back())});
            }
            for (int j = b.size()-1; j >= 0; j--) {
                a.push_back(b[j]);
            }
            b = {i};
        }
    }
    int co = 2;
    if (are_connected(a, b)) {
        vector<int> ch1 = {a.front(), a.back()}, ch2 = {b.front(), b.back()};
        sort(ch1.begin(), ch1.end());
        ch1.erase(unique(ch1.begin(), ch1.end()), ch1.end());
        sort(ch2.begin(), ch2.end());
        ch2.erase(unique(ch2.begin(), ch2.end()), ch2.end());
        if (!are_connected(ch1, ch2)) {
            // both become cycles that are connected via some edge?
            int l = 0, r = a.size()-1, e1, e2;
            while(l < r) {
                co++;
                int m = (l+r)/2;
                vector<int> in;
                for (int i = 0; i <= m; i++) {
                    in.push_back(a[i]);
                }
                if (are_connected(in, b)) {
                    r = m;
                } else {
                    l = m+1;
                }
            }
            e1 = a[l];
            l = 0, r = b.size()-1;
            while(l < r) {
                co++;
                int m = (l+r)/2;
                vector<int> in;
                for (int i = 0; i <= m; i++) {
                    in.push_back(b[i]);
                }
                if (are_connected({e1}, in)) {
                    r = m;
                } else {
                    l = m+1;
                }
            }
            e2 = b[l];
            vector<int> ans;
            for (int i = find(a.begin(), a.end(), e1) - a.begin()+1; i < a.size(); i++) {
                ans.push_back(a[i]);
            }
            for (int i = 0; i <= find(a.begin(), a.end(), e1) - a.begin(); i++) {
                ans.push_back(a[i]);
            }
            for (int i = find(b.begin(), b.end(), e2) - b.begin(); i < b.size(); i++) {
                ans.push_back(b[i]);
            }
            for (int i = 0; i < find(b.begin(), b.end(), e2) - b.begin(); i++) {
                ans.push_back(b[i]);
            }
            a = ans;
            b.clear();
        } else if (are_connected({a.front()}, {b.front()})) {
            reverse(a.begin(), a.end());
            for (int j = 0; j < b.size(); j++) {
                a.push_back(b[j]);
            }
            reverse(a.begin(), a.end());
            b.clear();
        } else if (are_connected({a.back()}, {b.front()})) {
            for (int j = 0; j < b.size(); j++) {
                a.push_back(b[j]);
            }
            b.clear();
        } else if (are_connected({a.front()}, {b.back()})) {
            reverse(a.begin(), a.end());
            for (int j = b.size()-1; j >= 0; j--) {
                a.push_back(b[j]);
            }
            reverse(a.begin(), a.end());
            b.clear();
        } else {
            for (int j = b.size()-1; j >= 0; j--) {
                a.push_back(b[j]);
            }
            b.clear();
        }
    }
    if (a.size() >= b.size()) {
        ans = a;
    } else {
        ans = b;
    }
    return ans;
}

Compilation message (stderr)

longesttrip.cpp: In function 'std::vector<int> longest_trip(int, int)':
longesttrip.cpp:84:72: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   84 |             for (int i = find(a.begin(), a.end(), e1) - a.begin()+1; i < a.size(); i++) {
      |                                                                      ~~^~~~~~~~~~
longesttrip.cpp:90:70: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   90 |             for (int i = find(b.begin(), b.end(), e2) - b.begin(); i < b.size(); i++) {
      |                                                                    ~~^~~~~~~~~~
longesttrip.cpp:100:31: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  100 |             for (int j = 0; j < b.size(); j++) {
      |                             ~~^~~~~~~~~~
longesttrip.cpp:106:31: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  106 |             for (int j = 0; j < b.size(); j++) {
      |                             ~~^~~~~~~~~~

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