Submission #1233567

#	Time	Username	Problem	Language	Result	Execution time	Memory
1233567		AMnu	Longest Trip (IOI23_longesttrip)	C++20	100 / 100	6 ms	416 KiB

longesttrip

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

vector<int> longest_trip(int N, int D) {
	vector <int> A, B;
	bool know = 0;
	A.push_back(0);
	B.push_back(1);
	for (int i=2;i<N;i++) {
		if (are_connected({i},{B.back()})) {
			B.push_back(i);
			if (B.size() == 2) {
				swap(B[0],B[1]);
			}
			else {
				know = 0;
			}
		}
		else if (know) {
			A.push_back(i);
			know = 0;
		}
		else if (are_connected({A.back()},{B.back()})) {
			while (!B.empty()) {
				A.push_back(B.back());
				B.pop_back();
			}
			B.push_back(i);
		}
		else {
			A.push_back(i);
			know = 1;
		}
	}
	if (!are_connected(A,B)) {
		if (A.size() > B.size()) {
			return A;
		}
		else {
			return B;
		}
	}
	vector <int> X, Y;
	X.push_back(A.back());
	Y.push_back(B.back());
	if (A.size() > 1) {
		X.push_back(A[0]);
	}
	if (B.size() > 1) {
		Y.push_back(B[0]);
	}
	if (are_connected(X,Y)) {
		if (are_connected({A.back()},{B.back()})) {
			while (!B.empty()) {
				A.push_back(B.back());
				B.pop_back();
			}
			return A;
		}
		if (are_connected({A.back()},{B[0]})) {
			for (int x : B) {
				A.push_back(x);
			}
			return A;
		}
		if (are_connected({A[0]},{B.back()})) {
			for (int x : A) {
				B.push_back(x);
			}
			return B;
		}
		reverse(A.begin(),A.end());
		for (int x : B) {
			A.push_back(x);
		}
		return A;
	}
	int L=0, R=A.size()-1;
	while (L < R) {
		int mid = (L+R)/2;
		vector <int> C;
		for (int i=L;i<=mid;i++) {
			C.push_back(A[i]);
		}
		if (are_connected(B,C)) {
			R = mid;
		}
		else {
			L = mid+1;
		}
	}
	vector <int> C;
	for (int i=L+1;i<A.size();i++) {
		C.push_back(A[i]);
	}
	for (int i=0;i<=L;i++) {
		C.push_back(A[i]);
	}
	L=0, R=B.size()-1;
	while (L < R) {
		int mid = (L+R)/2;
		vector <int> D;
		for (int i=L;i<=mid;i++) {
			D.push_back(B[i]);
		}
		if (are_connected({C.back()},D)) {
			R = mid;
		}
		else {
			L = mid+1;
		}
	}
	for (int i=L;i<B.size();i++) {
		C.push_back(B[i]);
	}
	for (int i=0;i<L;i++) {
		C.push_back(B[i]);
	}
	return C;
}

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