Submission #1070565

#	Time	Username	Problem	Language	Result	Execution time	Memory
1070565		zsombor	Longest Trip (IOI23_longesttrip)	C++17	30 / 100	14 ms	596 KiB

longesttrip

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

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

void pf(vector<int> &v, int x) {
    v.push_back(0);
    for (int i = v.size() - 1; i > 0; i--) v[i] = v[i - 1];
    v[0] = x;
}

void pb(vector<int> &v, int x) {
    v.push_back(x);
}

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

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

bool try_add(int x, vector<int> &v) {
    if (!v.size()) {
        pb(v, x);
        return true;
    }
    if (v.size() == 1) {
        if (are_connected({v[0]}, {x})) {
            pb(v, x);
            return true;
        }
        return false;
    }
    int y = v[0], z = v.back();
    if (are_connected({y}, {x})) {
        reverse(v.begin(), v.end());
        pb(v, x);
        return true;
    }
    if (are_connected({z}, {x})) {
        pb(v, x);
        return true;
    }
    int k = bin(x, v);
    if (k == -1) return false;
    vector<int> u;
    for (int i = k + 1; i < v.size(); i++) pb(u, v[i]);
    for (int i = 0; i <= k; i++) pb(u, v[i]);
    v = u;
    v.push_back(x);
    return true;
}

void solve() {
    for (int i = 2; i < n; i++) {
        if (are_connected({a.back()}, {b.back()})) {
            while (b.size()) {
                a.push_back(b.back());
                b.pop_back();
            }
            b.push_back(i);
            continue;
        }
        if (are_connected({a.back()}, {i})) a.push_back(i);
        else b.push_back(i);
    }
}

vector<int> longest_trip(int N, int D) {
    n = N;
    a = {0};
    b = {1};
    solve();

    if (a.size()<b.size()) swap(a,b);
    if (!try_add(a.back(),b)) return a;
    b.pop_back();
    while (b.size()) {
        a.push_back(b.back());
        b.pop_back();
    }
    return a;
}

Compilation message (stderr)

longesttrip.cpp: In function 'bool try_add(int, std::vector<int>&)':
longesttrip.cpp:60:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   60 |     for (int i = k + 1; i < v.size(); i++) pb(u, v[i]);
      |                         ~~^~~~~~~~~~

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