Submission #847521

#	Time	Username	Problem	Language	Result	Execution time	Memory
847521		rainboy	Longest Trip (IOI23_longesttrip)	C++17	5 / 100	9 ms	600 KiB

longesttrip

/* upsolved using some inspiration from EmeraldBlock */
#include "longesttrip.h"
#include <vector>

using namespace std;

typedef vector<int> vi;

const int N = 256;

int qu1[N], qu2[N], cnt1, cnt2;

vi longest_trip(int n, int d) {
	cnt1 = cnt2 = 0;
	for (int i = 0; i < n; i++)
		if (cnt1 == 0)
			qu1[cnt1++] = i;
		else if (cnt2 == 0)
			qu2[cnt2++] = i;
		else if (are_connected({ qu1[cnt1 - 1] }, { i }))
			qu1[cnt1++] = i;
		else if (i + 1 == n) {
			if (!are_connected({ qu2[cnt2 - 1] }, { i }))
				while (cnt2)
					qu1[cnt1++] = qu2[--cnt2];
			qu2[cnt2++] = i;
		} else {
			if (are_connected({ i }, { i + 1 })) {
				if (!are_connected({ qu2[cnt2 - 1] }, { i }))
					while (cnt2)
						qu1[cnt1++] = qu2[--cnt2];
				qu2[cnt2++] = i, qu2[cnt2++] = i + 1;
			} else {
				qu1[cnt1++] = i + 1;
				if (!are_connected({ qu2[cnt2 - 1] }, { i }))
					while (cnt2)
						qu1[cnt1++] = qu2[--cnt2];
				qu2[cnt2++] = i;
			}
			i++;
		}
	vi uu, vv, ww;
	if (cnt2 == 0)
		for (int h = 0; h < cnt1; h++)
			ww.push_back(qu1[h]);
	else if (cnt1 == 0)
		for (int h = 0; h < cnt2; h++)
			ww.push_back(qu2[h]);
	else {
		vi uu, vv;
		int lower = 0, upper = cnt1 + 1;
		while (upper - lower > 1) {
			int k = (lower + upper) / 2;
			uu.clear();
			for (int h = 0; h < k; h++)
				uu.push_back(qu1[(h - 1 + cnt1) % cnt1]);
			vv.clear();
			for (int h = 0; h < cnt2; h++)
				vv.push_back(qu2[h]);
			if (are_connected(uu, vv))
				upper = k;
			else
				lower = k;
		}
		int h1 = lower;
		if (h1 == cnt1) {
			if (cnt1 > cnt2)
				for (int h = 0; h < cnt1; h++)
					ww.push_back(qu1[h]);
			else
				for (int h = 0; h < cnt2; h++)
					ww.push_back(qu2[h]);
		} else {
			lower = 0, upper = cnt2;
			while (upper - lower > 1) {
				int k = (lower + upper) / 2;
				uu.clear();
				for (int h = 0; h < cnt1; h++)
					uu.push_back(qu1[h]);
				vv.clear();
				for (int h = 0; h < k; h++)
					vv.push_back(qu2[(h - 1 + cnt2) % cnt2]);
				if (are_connected(uu, vv))
					upper = k;
				else
					lower = k;
			}
			int h2 = lower;
			if (h1 == 1)
				for (int h = cnt1 - 1; h >= 0; h--)
					ww.push_back(qu1[h]);
			else
				for (int h = 0; h < cnt1; h++)
					ww.push_back(qu1[(h1 + h) % cnt1]);
			if (h2 == 1)
				for (int h = 0; h < cnt2; h++)
					ww.push_back(qu2[h]);
			else
				for (int h = cnt2 - 1; h >= 0; h--)
					ww.push_back(qu2[(h2 + h) % cnt2]);
		}
	}
	return ww;
}

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