Submission #782972

#	Time	Username	Problem	Language	Result	Execution time	Memory
782972		Elias	Building 4 (JOI20_building4)	C++17	100 / 100	202 ms	68972 KiB

building4

#ifndef _DEBUG
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#endif

#include <bits/stdc++.h>

using namespace std;

#define int long long
#define all(x) (x).begin(), (x).end()

template <class T>
istream &operator>>(istream &in, vector<T> &a)
{
	for (T &x : a)
		in >> x;
	return in;
}

template <class T>
ostream &operator<<(ostream &out, const vector<T> &a)
{
	for (T x : a)
		out << x << " ";
	out << "\n";
	return out;
}

struct Range
{
	int low, high;

	Range operator+(Range other)
	{
		if (low < 0)
			return other;

		if (other.low < 0)
			return *this;

		assert(max(low, other.low) <= min(high, other.high) + 1);

		return {min(low, other.low), max(high, other.high)};
	}

	Range operator+(int x)
	{
		return {low + x, high + x};
	}
};

signed main()
{
	cin.tie(0);
	ios_base::sync_with_stdio(false);

	int n;
	cin >> n;

	vector<int> a(2 * n);
	vector<int> b(2 * n);
	cin >> a >> b;

	vector<Range> rA(2 * n, {-1000000000, -1000000000}), rB(2 * n, {-1000000000, -1000000000});

	rA[0] = {0, 0};
	rB[0] = {1, 1};

	for (int i = 1; i < n * 2; i++)
	{
		if (a[i] >= a[i - 1])
			rA[i] = rA[i] + rA[i - 1];
		if (a[i] >= b[i - 1])
			rA[i] = rA[i] + rB[i - 1];
		if (b[i] >= a[i - 1])
			rB[i] = (rB[i] + rA[i - 1]);
		if (b[i] >= b[i - 1])
			rB[i] = (rB[i] + rB[i - 1]);
		rB[i] = rB[i] + 1;
	}

	string out;
	int needed = n;
	int last_taken = 10000000000000;

	while (rA.size())
	{
		if (needed >= rA.back().low && needed <= rA.back().high && a.back() <= last_taken)
		{
			out.push_back('A');
			last_taken = a.back();
		}
		else if (needed >= rB.back().low && needed <= rB.back().high && b.back() <= last_taken)
		{
			out.push_back('B');
			last_taken = b.back();
			needed--;
		}
		else
		{
			cout << -1;
			return 0;
		}
		rA.pop_back();
		rB.pop_back();
		a.pop_back();
		b.pop_back();
	}

	reverse(out.begin(), out.end());
	cout << out;
}

• Subtask 1: 11 / 11
• Subtask 2: 89 / 89