Submission #234104

#	Time	Username	Problem	Language	Result	Execution time	Memory
234104		ruler	Portals (BOI14_portals)	C++14	100 / 100	432 ms	46972 KiB

portals

// IOI 2021
#include <bits/stdc++.h>
using namespace std;

#define endl '\n'
#define ends ' '
#define die(x) return cout << x << endl, 0
#define all(v) v.begin(), v.end()
#define sz(x) (int)(x.size())
void debug_out() { cerr << endl; }
template <typename Head, typename... Tail>
void debug_out(Head H, Tail... T) { cerr << ends << H; debug_out(T...); }
#define debug(...) cerr << "{" << #__VA_ARGS__ << "}:", debug_out(__VA_ARGS__)
typedef long long ll;
typedef pair<int, int> pii;
const ll INF = 1e18;
const ll MOD = 1e9 + 7;
 
////////////////////////////////////////////////////////////////////

const int N = 1e3 + 2;

bool A[N][N];
int W[N][N], D[N][N];
pii X[4][N][N];
int DX[] = {+1, -1, 0, 0};
int DY[] = {0, 0, +1, -1};

int main() {

	ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
	mt19937 Rnd(time(0));
	
	memset(W, 63, sizeof W), memset(D, 63, sizeof D);

	int n, m; cin >> n >> m;
	pii src, dest;
	for (int i = 1; i <= n; i++) for (int j = 1; j <= m; j++) {
		char c; cin >> c;
		A[i][j] = (c != '#');
		if (c == 'S') src = make_pair(i, j);
		if (c == 'C') dest = make_pair(i, j);
	}
	for (int i = 1; i <= n; i++) for (int j = 1; j <= m; j++) if (A[i][j]) {
		X[0][i][j] = (A[i][j - 1] ? X[0][i][j - 1] : make_pair(i, j));
		X[1][i][j] = (A[i - 1][j] ? X[1][i - 1][j] : make_pair(i, j));
	}
	for (int i = n; i >= 1; i--) for (int j = m; j >= 1; j--) if (A[i][j]) {
		X[2][i][j] = (A[i][j + 1] ? X[2][i][j + 1] : make_pair(i, j));
		X[3][i][j] = (A[i + 1][j] ? X[3][i + 1][j] : make_pair(i, j));
	}
	queue<pii> Q;
	for (int i = 1; i <= n; i++) for (int j = 1; j <= m; j++) if (A[i][j] && !(A[i - 1][j] && A[i + 1][j] && A[i][j - 1] && A[i][j + 1])) W[i][j] = 0, Q.push(make_pair(i, j));
	while (!Q.empty()) {
		pii p = Q.front(); Q.pop();
		for (int i = 0; i < 4; i++) {
			pii q = make_pair(p.first + DX[i], p.second + DY[i]);
			if (A[q.first][q.second] && W[p.first][p.second] + 1 < W[q.first][q.second]) 
				W[q.first][q.second] = W[p.first][p.second] + 1, Q.push(q); 
		}
	}
	set< pair<int, pii> > S;
	D[src.first][src.second] = 0;
	S.insert(make_pair(0, src));
	while (!S.empty()) {
		pii p = S.begin()->second; S.erase(S.begin());
		for (int i = 0; i < 4; i++) {
			pii q = make_pair(p.first + DX[i], p.second + DY[i]);
			if (A[q.first][q.second] && D[p.first][p.second] + 1 < D[q.first][q.second]) 
				S.erase(make_pair(D[q.first][q.second], q)), D[q.first][q.second] = D[p.first][p.second] + 1, S.insert(make_pair(D[q.first][q.second], q)); 
			q = X[i][p.first][p.second];
			if (A[q.first][q.second] && D[p.first][p.second] + W[p.first][p.second] + 1 < D[q.first][q.second]) 
				S.erase(make_pair(D[q.first][q.second], q)), D[q.first][q.second] = D[p.first][p.second] + W[p.first][p.second] + 1, S.insert(make_pair(D[q.first][q.second], q));
		}
	}
	cout << D[dest.first][dest.second] << endl;

	return 0;
}

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