Submission #1004831

#	Time	Username	Problem	Language	Result	Execution time	Memory
1004831		Wael	Longest Trip (IOI23_longesttrip)	C++17	85 / 100	16 ms	860 KiB

longesttrip

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

using i64 = long long;

vector<int> longest_trip(int N, int D) {
    int n = N;
    
    auto ask = [&](int x, int y) -> bool {
        return are_connected(vector<int>{x}, vector<int>{y});
    };

    vector<int> a{0}, b;
    for (int i = 1; i < n; ++i) {
        if (ask(a.back(), i)) {
            a.push_back(i);
        } else {
            b.push_back(i);
        }
        if (b.size() && ask(b.back(), a.back())) {
            reverse(b.begin(), b.end());
            for (auto j : b) {
                a.push_back(j);
            }
            b.clear();
        }
    }

    if (b.size() && are_connected(a, b)) {
        if (are_connected(vector<int>{a.back()}, vector<int>(b.begin(), b.end())) == 0) {
            int l = 1, r = b.size();
            while (l <= r) {
                int mid = (l + r) / 2;
                if (are_connected(a, vector<int>(b.begin(), b.begin() + mid))) {
                    r = mid - 1;
                } else {
                    l = mid + 1;
                }
            }
            ++r;
            swap(b[r - 1], b.back());
            swap(a, b);
        }
        if (ask(a.back(), b.back())) {
            reverse(b.begin(), b.end());
        }
        int l = 1, r = b.size();
        while (l <= r) {
            int mid = (l + r) / 2;
            if (are_connected(vector<int>{a.back()}, vector<int>(b.begin(), b.begin() + mid))) {
                r = mid - 1;
            } else {
                l = mid + 1;
            }
        }
        --l;
        while (l--) {
            b.push_back(b[0]);
            b.erase(b.begin());
        }
        for (auto j : b) {
            a.push_back(j);
        }
        b.clear();
    } else {
        if (a.size() < b.size()) {
            swap(a, b);
        }
    }

    return a;
}

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