Submission #1207114

#	Time	Username	Problem	Language	Result	Execution time	Memory
1207114		Pekiban	Longest Trip (IOI23_longesttrip)	C++20	15 / 100	5 ms	408 KiB

longesttrip

#include "longesttrip.h"
#include <bits/stdc++.h>
#pragma GCC optimize("O3")

using namespace std;
#define pb push_back

vector<int> longest_trip(int n, int D) {
    if (D == 3) {
        vector<int> v(n);
        iota(v.begin(), v.end(), 0);
        return v;
    }
    if (D == 2) {
        deque<int> dq;
        dq = {0};
        set<int> s;
        for (int i = 1; i < n; ++i) s.insert(i);
        while (s.size() > 1) {
            int x = *s.begin(); s.erase(x);
            int y = *s.begin(); s.erase(y);
            if (are_connected({dq.back()}, {x})) {
                dq.pb(x);
                s.insert(y);
            }
            else {
                dq.pb(y);
                s.insert(x);
            }
        }
        int x = *s.begin();
        if (are_connected({dq.back()}, {x}))    
            dq.pb(x);
        else
            dq.push_front(x);
        vector<int> v(n); 
        for (int i = 0; i < n; ++i) v[i] = dq[i];
        return v;
    }
    if (D == 1) {
        vector<int> A = {0}, B;
        for (int i = 1; i < n; ++i) {
            bool a = are_connected({A.back()}, {i});
            if (B.empty()) {
                if (a)  
                    A.pb(i);
                else
                    B.pb(i);
            }
            else {
                bool b = are_connected({B.back()}, {i});
                if (a && b) {
                    A.pb(i);
                    reverse(B.begin(), B.end());
                    for (auto x : B)    A.pb(x);
                    B.clear();
                }
                else if (a)
                    A.pb(i);
                else
                    B.pb(i);
            }
        }
        if (B.empty())  return A;
        if (are_connected(A, B)) {
            auto a = A, b = B;
            while (a.size() > 1 || b.size() > 1) {
                if (a.size() > 1) {
                    vector<int> c[2];
                    for (int i = 0; i < a.size(); ++i) c[i%2].pb(a[i]);
                    if (are_connected({c[0]}, {b})) 
                        a = c[0];
                    else
                        a = c[1];
                }
                if (b.size() > 1) {
                    vector<int> c[2];
                    for (int i = 0; i < b.size(); ++i)  c[i%2].pb(b[i]);
                    if (are_connected({c[0]}, {a})) 
                        b = c[0];
                    else
                        b = c[1];
                }
            }
            int x = a[0], y = b[0];
            if (are_connected({A.back()}, {B.back()})) {
                while (A.back() != x) {
                    B.pb(A.back());
                    A.pop_back();
                }
            }
            else if (are_connected({A[0]}, {B.back()})) {
                reverse(A.begin(), A.end());
                while (A.back() != x) {
                    B.pb(A.back());
                    A.pop_back();
                }
            }
            else {
                vector<int> c;
                while (A.back() != x) {
                    c.pb(A.back());
                    A.pop_back();
                }
                reverse(A.begin(), A.end());
                while (!A.empty()) {
                    c.pb(A.back());
                    A.pop_back();
                }
            }
            if (are_connected({A[0]}, {B.back()})) {
                reverse(A.begin(), A.end());
                for (auto i : A)    B.pb(i);
                return B;
            }
            else if (are_connected({A[0]}, {B[0]})) {
                reverse(B.begin(), B.end());
                for (auto i : A)    B.pb(i);
                return B;
            }
            vector<int> c;
            while (B.back() != y) {
                c.pb(B.back());
                B.pop_back();
            }
            reverse(B.begin(), B.end());
            for (auto i : c)    B.pb(i);
            for (auto x : B)    A.pb(x);
            return A;
        }
        return A.size() > B.size() ? A : B;
    }
    return {};
}

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