Submission #730469

#	Time	Username	Problem	Language	Result	Execution time	Memory
730469		josanneo22	Exam (eJOI20_exam)	C++17	100 / 100	60 ms	8784 KiB

exam

#include <bits/stdc++.h>
 
int main() {
	using namespace std;
	ios_base::sync_with_stdio(false), cin.tie(nullptr);
 
	int N; cin >> N;
	vector<int> A(N); for (auto& a : A) cin >> a;
	vector<int> B(N); for (auto& b : B) cin >> b;
	vector<array<int, 2>> match(N, array<int, 2>{-1, -1});
	for (int z = 0; z < 2; z++) {
		unordered_map<int, int> in_stack;
		vector<int> stk; stk.reserve(N);
		for (int j = 0; j < N; j++) {
			int i = z ? N-1-j : j;
			while (!stk.empty() && stk.back() <= A[i]) {
				in_stack.erase(stk.back());
				stk.pop_back();
			}
			stk.push_back(A[i]);
			in_stack[A[i]] = i;
 
			if (in_stack.count(B[i])) {
				match[i][z] = in_stack[B[i]];
			}
		}
	}
	vector<int> V; V.reserve(2*N);
	for (int i = 0; i < N; i++) {
		if (match[i][1] != -1) {
			V.push_back(match[i][1]);
		}
		if (match[i][0] != -1 && match[i][0] != match[i][1]) {
			V.push_back(match[i][0]);
		}
	}
	vector<int> best; best.reserve(V.size());
	for (int v : V) {
		int mi = -1;
		int ma = int(best.size());
		while (ma - mi > 1) {
			int md = (mi + ma) / 2;
			if (v >= best[md]) mi = md;
			else ma = md;
		}
		if (ma == int(best.size())) best.push_back(v);
		else best[ma] = v;
	}
 
	cout << best.size() << '\n';
 
	return 0;
}

• Subtask 1: 14 / 14
• Subtask 2: 12 / 12
• Subtask 3: 13 / 13
• Subtask 4: 23 / 23
• Subtask 5: 16 / 16
• Subtask 6: 22 / 22