Submission #842336

#	Time	Username	Problem	Language	Result	Execution time	Memory
842336		SHZhang	Longest Trip (IOI23_longesttrip)	C++17	85 / 100	13 ms	940 KiB

longesttrip

#include "longesttrip.h"

#include <cstdio>
#include <vector>
#include <algorithm>
#include <utility>

using namespace std;

vector<int> longest_trip(int N, int D)
{
    vector<int> c1, c2;
    c1.push_back(0);
    for (int i = 1; i < N; i++) {
        if (c2.empty()) {
            if (are_connected({c1.back()}, {i})) {
                c1.push_back(i);
            } else {
                c2.push_back(i);
            }
        } else {
            bool conn1 = are_connected({c1.back()}, {i});
            bool conn2 = are_connected({c2.back()}, {i});
            if (conn1 && conn2) {
                reverse(c2.begin(), c2.end());
                c1.push_back(i);
                for (int i = 0; i < c2.size(); i++) {
                    c1.push_back(c2[i]);
                }
                c2.clear();
            } else if (conn1) {
                c1.push_back(i);
            } else {
                c2.push_back(i);
            }
        }
    }
    if (c2.empty()) {
        return c1;
    }
    if (!are_connected(c1, c2)) {
        if (c1.size() > c2.size()) {
            return c1;
        } else {
            return c2;
        }
    }
    if (c1.size() >= 2 && !are_connected({c1.front()}, {c1.back()})) {
        if (are_connected({c1.front()}, {c2.front()})) {
            reverse(c1.begin(), c1.end());
        }
        for (int i = 0; i < c2.size(); i++) {
            c1.push_back(c2[i]);
        }
        return c1;
    }
    if (c2.size() >= 2 && !are_connected({c2.front()}, {c2.back()})) {
        if (are_connected({c1.back()}, {c2.back()})) {
            reverse(c2.begin(), c2.end());
        }
        for (int i = 0; i < c2.size(); i++) {
            c1.push_back(c2[i]);
        }
        return c1;
    }
    int l1 = 1;
    int r1 = c1.size();
    while (l1 < r1) {
        int mid = (l1 + r1) / 2;
        vector<int> newc1;
        for (int i = 0; i < mid; i++) newc1.push_back(c1[i]);
        if (are_connected(newc1, c2)) {
            r1 = mid;
        } else {
            l1 = mid + 1;
        }
    }
    vector<int> c1pref;
    for (int i = 0; i < l1; i++) c1pref.push_back(c1[i]);
    int l2 = 1;
    int r2 = c2.size();
    while (l2 < r2) {
        int mid = (l2 + r2) / 2;
        vector<int> newc2;
        for (int i = 0; i < mid; i++) newc2.push_back(c2[i]);
        if (are_connected(c1pref, newc2)) {
            r2 = mid;
        } else {
            l2 = mid + 1;
        }
    }
    vector<int> ans;
    for (int i = l1; i < c1.size(); i++) ans.push_back(c1[i]);
    for (int i = 0; i < l1; i++) ans.push_back(c1[i]);
    for (int i = l2 - 1; i < c2.size(); i++) ans.push_back(c2[i]);
    for (int i = 0; i < l2 - 1; i++) ans.push_back(c2[i]);
    return ans;
}

Compilation message (stderr)

longesttrip.cpp: In function 'std::vector<int> longest_trip(int, int)':
longesttrip.cpp:27:35: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   27 |                 for (int i = 0; i < c2.size(); i++) {
      |                                 ~~^~~~~~~~~~~
longesttrip.cpp:52:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   52 |         for (int i = 0; i < c2.size(); i++) {
      |                         ~~^~~~~~~~~~~
longesttrip.cpp:61:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   61 |         for (int i = 0; i < c2.size(); i++) {
      |                         ~~^~~~~~~~~~~
longesttrip.cpp:93:24: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   93 |     for (int i = l1; i < c1.size(); i++) ans.push_back(c1[i]);
      |                      ~~^~~~~~~~~~~
longesttrip.cpp:95:28: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   95 |     for (int i = l2 - 1; i < c2.size(); i++) ans.push_back(c2[i]);
      |                          ~~^~~~~~~~~~~

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