Submission #1311751

#	Time	Username	Problem	Language	Result	Execution time	Memory
1311751		madamadam3	Xylophone (JOI18_xylophone)	C++20	100 / 100	21 ms	724 KiB

xylophone

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

using namespace std;

void solve(int N) {
	int value = query(1, N);
	int L = 1, hi = N;
	while (L < hi) {
		int mid = L + (hi - L + 1) / 2;
		if (query(mid, N) == value) L = mid;
		else hi = mid - 1;
	}

	vector<int> ans(N+1, -1);
	set<int> avail; for (int i = 2; i <= N; i++) avail.insert(i);
	vector<int> indices; for (int i = L; i <= N; i++) indices.push_back(i);
	for (int i = L-1; i >= 1; i--) indices.push_back(i);

	for (int i : indices) {
		if (i == L) ans[i] = 1;
		else if (i == L+1) ans[i] = 1 + query(L, i);
		else if (i == L-1) ans[i] = 1 + query(i, L);
		else {
			int dx = i > L ? query(i-1, i) : query(i, i+1);
			int p1 = i > L ? i-1 : i+1, p2 = i > L ? i-2 : i+2;
			
			int a = ans[p1] + dx, b = ans[p1] - dx;
			int x = ans[p2], y = ans[p1];

			// y < a < x, y < x < a, x < y < a
			// x < b < y, b < y < x, b < x < y
			if (!avail.count(a)) ans[i] = b;
			else if (!avail.count(b)) ans[i] = a;
			else {
				int dy = i > L ? query(i-2, i) : query(i, i+2);
				if (y < a && a < x && dy == x-y) ans[i] = a;
				else if (y < x && x < a && dy == a-y) ans[i] = a;
				else if (x < y && y < a && dy == a-x) ans[i] = a;
				else if (x < b && b < y && dy == y-x) ans[i] = b;
				else if (b < y && y < x && dy == x-b) ans[i] = b;
				else if (b < x && x < y && dy == y-b) ans[i] = b;
			}
		}

		avail.erase(ans[i]);
	}

	for(int i = 1; i <= N; i++) answer(i, ans[i]);
}

• Subtask 1: 11 / 11
• Subtask 2: 36 / 36
• Subtask 3: 53 / 53