Submission #976351

#	Time	Username	Problem	Language	Result	Execution time	Memory
976351		vjudge1	Awesome Arrowland Adventure (eJOI19_adventure)	C++17	10 / 100	2065 ms	102400 KiB

adventure

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

using ll = long long;

const int dx[4] = {-1, 0, 1, 0}, dy[4] = {0, 1, 0, -1};
const char c[4] = {'N', 'E', 'S', 'W'};

int n, m, ans = 1e9;
vector<string> v; 
map<char, int> id;

bool inside(int i, int j) {
	return i >= 0 && i < n && j >= 0 && j < m;
}

bool solvable() {
	if (v[0][0] == 'X') return 0;

	vector<vector<bool>> vis(n, vector<bool>(m, 0));

	queue<pair<int, int>> bfs;
	bfs.push({0, 0});
	vis[0][0] = 1;

	while (!bfs.empty()) {
		auto [x, y] = bfs.front();
		bfs.pop();

		if (v[x][y] == 'X') continue;

		if (inside(x + 1, y)) {
			bfs.push(make_pair(x + 1, y));
			vis[x + 1][y] = 1;
		}

		if (inside(x, y + 1)) {
			bfs.push(make_pair(x, y + 1));
			vis[x][y + 1] = 1;
		}
	}

	return vis[n-1][m-1];
}

int dist(char a, char b) {
	int ret = (id[b] - id[a]) % 4;
	if (ret < 0) ret += 4;
	return ret;
}

int f(tuple<int, int, int> a) {
	auto [g, i, j] = a;
	return (g + abs(n - i - 1) + abs(m - j - 1));
}

signed main() {
	id['N'] = 1;
	id['E'] = 2;
	id['S'] = 3;
	id['W'] = 4;

	cin >> n >> m;

	v.resize(n);

	for (int i = 0; i<n; i++) {
		cin >> v[i];
	}

	if (n == 1 && m == 1) {
		cout << 0 << '\n';
		return 0;
	}

	if (!solvable()) {
		cout << -1 << '\n';
		return 0;
	}

	auto cmp = [&](tuple<int, int, int> &a, tuple<int, int, int> &b) {
		return f(a) > f(b);
	};

	priority_queue<tuple<int, int, int>, vector<tuple<int, int, int>>, decltype(cmp)> pq(cmp);
	pq.push({0, 0, 0});

	while (!pq.empty()) {
		auto [g, i, j] = pq.top();
		pq.pop();

		if (i == n-1 && j == m-1) {
			ans = g;
			break;
		}

		if (v[i][j] == 'X') continue;

		for (int k = 0; k < 4; k++) {
			if (inside(i + dx[k], j + dy[k])) pq.push({g + dist(v[i][j], c[k]), i + dx[k], j + dy[k]});
		}
	}

	cout << ans << '\n';
}

• Subtask 1: 10 / 10
• Subtask 2: 0 / 12
• Subtask 3: 0 / 12
• Subtask 4: 0 / 16
• Subtask 5: 0 / 50