Submission #1214619

#	Time	Username	Problem	Language	Result	Execution time	Memory
1214619		trimkus	Longest Trip (IOI23_longesttrip)	C++20	85 / 100	6 ms	428 KiB

longesttrip

#include "longesttrip.h"
#include <bits/stdc++.h>

using namespace std;
int N;
const int MAXN = 256;
vector<int> adj[MAXN];


void connect(vector<int>& path1, vector<int>& path2) {
    reverse(begin(path2), end(path2));
    for (int j = 0; j < (int)path2.size(); ++j) {
        path1.push_back(path2[j]);
    }
    path2.clear();
}

std::vector<int> longest_trip(int _N, int D)
{
    N = _N;
    vector<int> idx(N);
    iota(begin(idx), end(idx), 0);
    mt19937 rng(5);
    shuffle(begin(idx), end(idx), rng);
    vector<int> path1{idx[0]}, path2{idx[1]};
    for (int j = 2; j < N; ++j) {
        int i = idx[j];
        if (are_connected({path1.back()}, {i})) {
            path1.push_back(i);
        } else if (are_connected({path2.back()}, {i})) {
            path2.push_back(i);
        } else {
            assert(are_connected({path1.back()}, {path2.back()}));
            connect(path1, path2);
            path2.push_back(i);
        }
    }
    if (path1.size() < path2.size()) swap(path1, path2);
    if (path2.size() == 0) return path1;
    if (!are_connected(path1, path2)) return path1;
    if (are_connected({path1.back()}, {path2.back()})) {
        connect(path1, path2);
        return path1;
    }
    reverse(begin(path1), end(path1));
    if (are_connected({path1.back()}, {path2.back()})) {
        connect(path1, path2);
        return path1;
    }
    reverse(begin(path1), end(path1));
    reverse(begin(path2), end(path2));
    if (are_connected({path1.back()}, {path2.back()})) {
        connect(path1, path2);
        return path1;
    }
    reverse(begin(path1), end(path1));
    if (are_connected({path1.back()}, {path2.back()})) {
        connect(path1, path2);
        return path1;
    }
    reverse(begin(path1), end(path1));
    reverse(begin(path2), end(path2));
    cerr << "Path1 = ";
    for (auto& u : path1) {
        cerr << u << " ";
    }
    cerr << "\nPath2 = ";
    for (auto& u : path2) {
        cerr << u << " ";
    }
    cerr << "\n";
    vector<int> super_path;
    int l1 = 0, r1 = (int)path1.size();
    int l2 = 0, r2 = (int)path2.size();
    while (r1 - l1 > 1) {
        int m1 = (l1 + r1) / 2;
        if (are_connected(vector<int>(begin(path1) + l1, begin(path1) + m1),
            vector<int>(begin(path2) + l2, begin(path2) + r2))) {
            r1 = m1;
        } else {
            l1 = m1;
        }
    }
    while (r2 - l2 > 1) {
        int m2 = (l2 + r2) / 2;
        if (are_connected(vector<int>(begin(path1) + l1, begin(path1) + r1),
            vector<int>(begin(path2) + l2, begin(path2) + m2))) {
            r2 = m2;
        } else {
            l2 = m2;
        }
    }
    assert(l1 < (int)path1.size());
    assert(l2 < (int)path2.size());
    assert(are_connected(vector<int>(begin(path1) + l1, begin(path1) + r1),
            vector<int>(begin(path2) + l2, begin(path2) + r2)));
    // assert(r1 != (int)path1.size() && r2 != (int)path2.size());
    // if (r1 == (int)path1.size()) r1 -= 1;
    // if (r2 == (int)path2.size()) r2 -= 1;
    rotate(begin(path1), begin(path1) + l1, end(path1));
    reverse(begin(path1), end(path1));
    rotate(begin(path2), begin(path2) + l2, end(path2));
    for (int i = 0; i < (int)path2.size(); ++i) {
        path1.push_back(path2[i]);
    }
    return path1;
}

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