Submission #771271

#	Time	Username	Problem	Language	Result	Execution time	Memory
771271		IBory	Jakarta Skyscrapers (APIO15_skyscraper)	C++17	100 / 100	967 ms	122396 KiB

skyscraper

#pragma GCC optimize("O3")
#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")

#include <bits/stdc++.h>
#define pii pair<int, int>
using namespace std;

const int MAX = 9999999;
vector<int> G[30003];
int D[MAX], L[MAX];
pii B[MAX];

int main() {
	ios::sync_with_stdio(0); cin.tie(0);
	int N, M;
	cin >> N >> M;
	map<pii, vector<int>> make;
	pii S, E;
	for (int i = 0; i < M; ++i) {
		int b, p;
		cin >> b >> p; b++;
		if (i == 0) S = { b, p };
		if (i == 1) E = { b, p };
		make[{p, b % p}].push_back(b);
	}

	int node = N + 1, SN, EN;
	for (auto& [q, v] : make) {
		auto [p, i] = q;
		if (!i) i += p;
		vector<int> fr;
		int init = node;
		B[init] = { p, i };
		for (int j = i; j <= N; j += p) {
			if (S == pii{ j, p }) SN = node;
			if (E == pii{ j, p }) EN = node;
			L[node] = init;
			fr.push_back(node++);
		}
		for (int n : v) {
			G[n].push_back(-fr[(n - 1) / p]);
		}
	}
	L[node] = 1;
	make.clear();

	memset(D, 0x3f, sizeof(D));
	D[SN] = 0;
	deque<int> Q;
	Q.push_back(SN);
	while (!Q.empty()) {
		int cur = Q.front(); Q.pop_front();
		if (cur == EN) break;

		if (cur <= N) {
			for (int next : G[cur]) {
				int d = 1;
				if (next < 0) {
					d = 0;
					next *= -1;
				}
				if (D[cur] + d >= D[next]) continue;
				D[next] = D[cur] + d;
				if (d == 0) Q.push_front(next);
				else Q.push_back(next);
			}
		}
		else {
			vector<int> AG;
			int t = L[cur];
			int RN = B[t].second + B[t].first * (cur - t);
			if (L[cur] != cur) AG.push_back(cur - 1);
			if (L[cur + 1] != (cur + 1)) AG.push_back(cur + 1);
			AG.push_back(-RN);

			for (int next : AG) {
				int d = 1;
				if (next < 0) {
					d = 0;
					next *= -1;
				}
				if (D[cur] + d >= D[next]) continue;
				D[next] = D[cur] + d;
				if (d == 0) Q.push_front(next);
				else Q.push_back(next);
			}
		}
	}

	cout << (D[EN] > 1E9 ? -1 : D[EN]);
	return 0;
}

Compilation message (stderr)

skyscraper.cpp: In function 'int main()':
skyscraper.cpp:91:15: warning: 'EN' may be used uninitialized in this function [-Wmaybe-uninitialized]
   91 |  cout << (D[EN] > 1E9 ? -1 : D[EN]);
      |           ~~~~^

• Subtask 1: 10 / 10
• Subtask 2: 12 / 12
• Subtask 3: 14 / 14
• Subtask 4: 21 / 21
• Subtask 5: 43 / 43