Submission #1099635

#	Time	Username	Problem	Language	Result	Execution time	Memory
1099635		stomic07	Portals (BOI14_portals)	C++17	70 / 100	1051 ms	26180 KiB

portals

#include <bits/stdc++.h>
using namespace std;

const int N = 1002;
int dozida[N][N];
int bio[N][N];
int ubacen[N][N];
int xmov[4] = {0, 1, 0, -1};
int ymov[4] = {-1, 0, 1, 0};

void reset(){
	for (int i=0; i<N; ++i){
		for (int j=0; j<N; ++j){
			dozida[i][j] = -1;
			bio[i][j] = -1;
			ubacen[i][j] = -1;
		}
	}
}

void bfs_odzida(const vector<string>& v, vector<pair<int, int>>& fronta){
	vector<pair<int, int>> novi;
	for (int step = 0; !fronta.empty(); ++step){
		novi.clear();
		for (int i=0; i<fronta.size(); ++i){
			pair<int, int> curr = fronta[i];
			if (dozida[curr.first][curr.second] != -1) continue;
			dozida[curr.first][curr.second] = step;
			for (int j=0; j<4; ++j){
				int y = curr.first + ymov[j];
				int x = curr.second + xmov[j];
				if (v[y][x] == '#') continue;
				if (dozida[y][x] != -1) continue;
				novi.push_back(make_pair(y, x));
			}
		}
		fronta.swap(novi);
	}
}

vector<pair<int, int>> moguci_portal(const vector<string>& v, const pair<int, int>& point){
	vector<pair<int, int>> ret;
	for (int i=0; i<4; ++i){
		for (int j=1; ; ++j){
			int y = point.first + ymov[i] * j;
			int x = point.second + xmov[i] * j;
			if (v[y][x] == '#'){
				ret.push_back(make_pair(y - ymov[i], x - xmov[i]));
				break;
			}
		}
	}
	return ret;
}

void dijkstra(const vector<string>& v, const pair<int, int>& start, const pair<int, int>& cilj){
	using el_t = pair<int, pair<int, int>>;
	auto cmp = [](const auto& l, const auto& r){return r < l;};
	vector<el_t> que;
	que.push_back(make_pair(0, start));
	ubacen[start.first][start.second] = 0;
	while (!que.empty()){
		el_t poz = *que.begin();
		pop_heap(que.begin(), que.end(), cmp);
		que.pop_back();
		pair<int, int> curr = poz.second;
		if (bio[curr.first][curr.second] != -1) continue;
		bio[curr.first][curr.second] = poz.first;
		if (curr == cilj) return;
		for (int i=0; i<4; ++i){
			int y = curr.first + ymov[i];
			int x = curr.second + xmov[i];
			if (v[y][x] == '#') continue;
			if (ubacen[y][x] != -1 && ubacen[y][x] <= poz.first + 1) continue;
			que.push_back(make_pair(poz.first + 1, make_pair(y, x)));
			push_heap(que.begin(), que.end(), cmp);
			ubacen[y][x] = poz.first + 1;
		}
		vector<pair<int, int>> krajevi = moguci_portal(v, curr);
		for (int i=0; i<krajevi.size(); ++i){
			int y = krajevi[i].first;
			int x = krajevi[i].second;
			if (ubacen[y][x] != -1 && ubacen[y][x] <= poz.first + dozida[curr.first][curr.second] + 1) continue;
			que.push_back(make_pair(poz.first + dozida[curr.first][curr.second] + 1, krajevi[i]));
			push_heap(que.begin(), que.end(), cmp);
			ubacen[y][x] = poz.first + dozida[curr.first][curr.second] + 1;
		}
	}
}

int main(){
	reset();
	int n, m;
	cin >> n >> m;
	string nule = "";
	for (int i=0; i<m+2; ++i){
		nule += '#';
	}
	vector<string> v;
	v.push_back(nule);
	pair<int, int> start;
	pair<int, int> cilj;
	for (int i=0; i<n; ++i){
		string s;
		cin >> s;
		for (int j=0; j<s.size(); ++j){
			if (s[j] == 'S'){
				start.first = i+1;
				start.second = j+1;
			}
			if (s[j] == 'C'){
				cilj.first = i+1;
				cilj.second = j+1;
			}
		}
		s = "#" + s + "#";
		v.push_back(s);
	}
	v.push_back(nule);
	vector<pair<int, int>> zidni;
	for (int i=1; i<n+1; ++i){
		for (int j=1; j<m+1; ++j){
			if (v[i][j] == '#') continue;
			for (int k=0; k<4; ++k){
				if (v[i + ymov[k]][j + xmov[k]] == '#'){
					zidni.push_back(make_pair(i, j));
					break;
				}
			}
		}
	}
	bfs_odzida(v, zidni);
	dijkstra(v, start, cilj);
	cout << bio[cilj.first][cilj.second] << "\n";
	return 0;
}

Compilation message (stderr)

portals.cpp: In function 'void bfs_odzida(const std::vector<std::__cxx11::basic_string<char> >&, std::vector<std::pair<int, int> >&)':
portals.cpp:25:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   25 |   for (int i=0; i<fronta.size(); ++i){
      |                 ~^~~~~~~~~~~~~~
portals.cpp: In function 'void dijkstra(const std::vector<std::__cxx11::basic_string<char> >&, const std::pair<int, int>&, const std::pair<int, int>&)':
portals.cpp:80:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   80 |   for (int i=0; i<krajevi.size(); ++i){
      |                 ~^~~~~~~~~~~~~~~
portals.cpp: In function 'int main()':
portals.cpp:106:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  106 |   for (int j=0; j<s.size(); ++j){
      |                 ~^~~~~~~~~

• Subtask 1: 11 / 11
• Subtask 2: 20 / 20
• Subtask 3: 20 / 20
• Subtask 4: 19 / 19
• Subtask 5: 0 / 30