Submission #853240

#	Time	Username	Problem	Language	Result	Execution time	Memory
853240		NK_	Portals (BOI14_portals)	C++17	0 / 100	1 ms	344 KiB

portals

// Success consists of going from failure to failure without loss of enthusiasm
#include <bits/stdc++.h>
 
using namespace std;
 
#define nl '\n'
#define pb push_back
#define pf push_front
 
#define mp make_pair
#define f first
#define s second
#define sz(x) int(x.size())
 
template<class T> using V = vector<T>;
using pi = pair<int, int>;
using vi = V<int>;
using vpi = V<pi>;
 
using ll = long long;
using pl = pair<ll, ll>;
using vpl = V<pl>;
using vl = V<ll>;
 
using db = long double;
 
template<class T> using pq = priority_queue<T, V<T>, greater<T>>;
 
const int MOD = 1e9 + 7;
const ll INFL = ll(1e17);
const int LG = 18;

int dx[4] = {0, 0, -1, 1};
int dy[4] = {-1, 1, 0, 0};

int main() {
	cin.tie(0)->sync_with_stdio(0);

	int N, M; cin >> N >> M;

	N += 2, M += 2;
	V<string> A(N, string(M, '#'));

	for(int i = 1; i < N-1; i++) {
		string t; cin >> t; 
		t = "#"+t+"#";
		A[i] = t;
	}

	V<vi> W(N, vi(M, MOD)), vis(N, vi(M, 0)); 
	{
		queue<pi> q; 
		for(int i = 0; i < N; i++) for(int j = 0; j < M; j++) {
			if (A[i][j] == '#') {
				W[i][j] = 0;
				q.push(mp(i, j));
			}
		}

		while(sz(q)) {
			auto [r, c] = q.front(); q.pop();
			
			if (vis[r][c]) continue;
			vis[r][c] = 1;

			for(int d = 0; d < 4; d++) {
				int nr = r + dx[d], nc = c + dy[d];
				if (nr < 0 || nc < 0 || nr >= N || nc >= M) continue;

				if (W[nr][nc] > W[r][c] + 1) {
					W[nr][nc] = W[r][c] + 1;
					q.push(mp(nr, nc));
				}
			}

		}	
	}

	// for(auto x : A) cout << x << nl;

	// for(auto v : W) {
	// 	for(auto x : v) cout << x << " ";
	// 	cout << endl;
	// }

	pi S, C; for(int i = 0; i < N; i++) for(int j = 0; j < M; j++) {
		if (A[i][j] == 'S') {
			A[i][j] = '.';
			S = mp(i, j);
		}

		if (A[i][j] == 'C') {
			A[i][j] = '.';
			C = mp(i, j);
		}
	}	

	V<V<vpi>> port(N, V<vpi>(M));

	{
		pi cur;
		for(int i = 0; i < N; i++) {
			for(int j = 0; j < M; j++) {
				if (A[i][j] == '#') continue;
				if (A[i][j-1] == '#') cur = mp(i, j);
				port[i][j].pb(cur);
			}
		}
	}

	{
		pi cur;
		for(int i = 0; i < N; i++) {
			for(int j = M - 1; j >= 0; j--) {
				if (A[i][j] == '#') continue;
				if (A[i][j+1] == '#') cur = mp(i, j);
				port[i][j].pb(cur);
			}
		}
	}

	{
		pi cur;
		for(int j = 0; j < M; j++) {
			for(int i = 0; i < N; i++) {
				if (A[i][j] == '#') continue;
				if (A[i-1][j] == '#') cur = mp(i, j);
				port[i][j].pb(cur);
			}
		}
	}

	{
		pi cur;
		for(int j = 0; j < M; j++) {
			for(int i = N - 1; i >= 0; i--) {
				if (A[i][j] == '#') continue;
				if (A[i+1][j] == '#') cur = mp(i, j);
				port[i][j].pb(cur);
			}
		}
	}	

	V<vi> D(N, vi(M, MOD));
	pq<array<int, 3>> q; q.push({D[S.f][S.s] = 0, S.f, S.s});

	while(sz(q)) {
		auto [d, r, c] = q.top(); q.pop();

		if (D[r][c] != d) continue;
		// cout << r << " " << c << " => " << d << endl;

		for(int dir = 0; dir < 4; dir++) {
			int nr = r + dx[dir], nc = c + dy[dir];
			if (nr < 0 || nc < 0 || nr >= N || nc >= M) continue;
			if (D[nr][nc] > D[r][c]+1) q.push({D[nr][nc] = D[r][c]+1, nr, nc});
		}

		for(auto p : port[r][c]) {
			auto [nr, nc] = p;
			// cout << nr << ", " << nc << endl;
			if (D[nr][nc] > D[r][c]+W[r][c]) q.push({D[nr][nc] = D[r][c]+W[r][c], nr, nc});
		}
	}

	cout << D[C.f][C.s] << nl;


	exit(0-0);
} 	

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