Submission #1070933

#	Time	Username	Problem	Language	Result	Execution time	Memory
1070933		zsombor	Longest Trip (IOI23_longesttrip)	C++17	15 / 100	12 ms	600 KiB

longesttrip

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

int n;
vector<int> a;
vector<int> b;

void solve() {
    for (int i = 2; i < n - 1; i += 2) {
        int x = i, y = i + 1;
        bool A = are_connected({x}, {a.back()});
        bool B = are_connected({x}, {b.back()});
        if (are_connected({x}, {y})) {
            if (A) {
                a.push_back(x);
                a.push_back(y);
            }
            if (!A && B) {
                b.push_back(x);
                b.push_back(y);
            }
            if (!A && !B) {
                while (b.size()) {
                    a.push_back(b.back());
                    b.pop_back();
                }
                b.push_back(x);
                b.push_back(y);
            }
        } else {
            if (A == B) {
                if (!A) swap(x, y);
                a.push_back(x);
                while (b.size()) {
                    a.push_back(b.back());
                    b.pop_back();
                }
                b.push_back(y);
            } else {
                if (!A) swap(x, y);
                a.push_back(x);
                b.push_back(y);
            }
        }
    }
    if (n % 2) {
        if (are_connected({a.back()}, {b.back()})) {
            while (b.size()) {
                a.push_back(b.back());
                b.pop_back();
            }
        }
        if (are_connected({n - 1}, {a.back()})) a.push_back(n - 1);
        else b.push_back(n - 1);
    }
}

bool query(vector<int> &x, vector<int> &v, int l, int r) {
    vector<int> u;
    for (int i = l; i < r; i++) u.push_back(v[i]);
    return are_connected(x, u);
}

int bin(vector<int> x, vector<int> &v) {
    int l = 0, r = v.size(), m;
    while (r - l > 1) {
        m = (l + r) / 2;
        (query(x, v, l, m) ? r = m : l = m);
    }
    return l;
}

vector<int> longest_trip(int N, int D) {
    n = N;
    a = {0};
    b = {1};
    solve();
    if (a.size() < b.size()) swap(a, b);
    if (!b.size() || !are_connected(a, b)) return a;

    bool A = are_connected({a[0]}, {b.back()});
    bool B = are_connected({b[0]}, {a.back()});
    bool C = are_connected({a.back()}, {b.back()});
    if (A) reverse(a.begin(), a.end());
    if (!A && B) reverse(b.begin(), b.end());
    if (A || B || C) {
        while (b.size()) {
            a.push_back(b.back());
            b.pop_back();
        }
        return a;
    }

    int x = bin(b, a);
    int y = bin({a[x]}, b);
    vector<int> u;
    for (int i = x + 1; i < a.size(); i++) u.push_back(a[i]);
    for (int i = 0; i <= x; i++) u.push_back(a[i]);
    for (int i = y; i < b.size(); i++) u.push_back(b[i]);
    for (int i = 0; i < y; i++) u.push_back(a[i]);
    return u;
}

Compilation message (stderr)

longesttrip.cpp: In function 'std::vector<int> longest_trip(int, int)':
longesttrip.cpp:98:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   98 |     for (int i = x + 1; i < a.size(); i++) u.push_back(a[i]);
      |                         ~~^~~~~~~~~~
longesttrip.cpp:100:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  100 |     for (int i = y; i < b.size(); i++) u.push_back(b[i]);
      |                     ~~^~~~~~~~~~

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