Submission #439934

#	Time	Username	Problem	Language	Result	Execution time	Memory
439934		elazarkoren	Awesome Arrowland Adventure (eJOI19_adventure)	C++17	100 / 100	151 ms	21192 KiB

adventure

#include <iostream>
#include <vector>
#include <algorithm>
#include <queue>
#define chkmin(a, b) a = min(a, b)
#define x first
#define y second
using namespace std;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef pair<int, int> pii;
typedef vector<pii> vii;
typedef vector<bool> vb;
typedef vector<vb> vvb;

const int infinity = 1e9;

//int ans = infinity;

int dir_x[] = {-1, 0, 1, 0};
int dir_y[] = {0, 1, 0, -1};
int n, m;

//void Dfs(vvi &graph, int x, int y, vvb &visited, int count) {
//    if (x < 0 || x >= n || y < 0 || y >= m) return;
//    if (visited[x][y]) return;
//    if (x == n - 1 && y == m - 1) {
//        chkmin(ans, count);
//        return;
//    }
//    if (graph[x][y] == 4) return;
//    visited[x][y] = true;
//    for (int i = 0; i < 4; i++) {
//        Dfs(graph, x + dir_x[graph[x][y]], y + dir_y[graph[x][y]], visited, count + i);
//        graph[x][y]++;
//        graph[x][y] %= 4;
//    }
//    visited[x][y] = false;
//}

inline int Val(int i, int j) {
    return i + n * j;
}

vector<vii> graph;
int Dijkstra() {
    vi distances(n * m, infinity);
    vb visited(n * m);
    distances[0] = 0;
    priority_queue<pii, vii, greater<pii>> pq;
    pq.push({0, 0});
    while (!pq.empty()) {
        int node = pq.top().y, d = pq.top().x;
        pq.pop();
        if (visited[node]) continue;
        visited[node] = true;
        for (pii neighbor : graph[node]) {
            if (distances[neighbor.x] > neighbor.y + d) {
                distances[neighbor.x] = neighbor.y + d;
                pq.push({neighbor.y + d, neighbor.x});
            }
        }
    }
    return distances[n * m - 1];
}

int main() {
    cin >> n >> m;
    graph.resize(n * m);
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < m; j++) {
            char c;
            cin >> c;
            int curr = 0;
            if (c == 'X') {
                curr = 4;
            } else if (c == 'S') {
                curr = 2;
            } else if (c == 'W') {
                curr = 3;
            } else if (c == 'E') {
                curr = 1;
            }
            int node = Val(i, j);
            if (curr != 4) {
                for (int k = 0; k < 4; k++) {
                    i += dir_x[k], j += dir_y[k];
                    if (0 <= i && i < n && 0 <= j && j < m) {
                        graph[node].push_back({Val(i, j), (k - curr + 4) % 4});
                    }
                    i -= dir_x[k], j -= dir_y[k];
                }
            }
        }
    }
//    vvb visited(n, vb(m));
//    Dfs(graph, 0, 0, visited, 0);
    int ans = Dijkstra();
    cout << (ans == infinity ? -1 : ans);
    return 0;
}

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