提出 #61382370

---

ソースコード 拡げる

#include <iostream>
#include <vector>
#include <queue>
#include <tuple>
#include <cstring>

using namespace std;

const int dx[2][4] = {{-1, 1, 0, 0}, {0, 0, -1, 1}}; // Direction: vertical, horizontal
const int dy[2][4] = {{0, 0, -1, 1}, {-1, 1, 0, 0}}; // Alternating directions
const int INF = 1e9;

int H, W;
vector<string> grid;

int bfs(int startX, int startY, int goalX, int goalY) {
    // Queue for BFS: (x, y, moves, last direction)
    queue<tuple<int, int, int, int>> q;
    bool visited[1000][1000][2]; // Visited array for (x, y, direction)
    memset(visited, false, sizeof(visited));

    // Push the start position
    q.emplace(startX, startY, 0, 0); // Vertical start
    q.emplace(startX, startY, 0, 1); // Horizontal start
    visited[startX][startY][0] = true;
    visited[startX][startY][1] = true;

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

        // If we reach the goal, return the moves
        if (x == goalX && y == goalY) {
            return moves;
        }

        // Alternate direction for the next move
        int nextDir = 1 - dir;

        // Explore neighbors in the allowed direction
        for (int i = 0; i < 4; ++i) {
            int nx = x + dx[nextDir][i];
            int ny = y + dy[nextDir][i];

            // Check bounds and obstacles
            if (nx >= 0 && nx < H && ny >= 0 && ny < W && grid[nx][ny] != '#') {
                if (!visited[nx][ny][nextDir]) {
                    visited[nx][ny][nextDir] = true;
                    q.emplace(nx, ny, moves + 1, nextDir);
                }
            }
        }
    }

    // If the goal is not reachable
    return -1;
}

int main() {
    // Input
    cin >> H >> W;
    grid.resize(H);

    int startX = -1, startY = -1, goalX = -1, goalY = -1;

    for (int i = 0; i < H; ++i) {
        cin >> grid[i];
        for (int j = 0; j < W; ++j) {
            if (grid[i][j] == 'S') {
                startX = i;
                startY = j;
            } else if (grid[i][j] == 'G') {
                goalX = i;
                goalY = j;
            }
        }
    }

    // Perform BFS
    int result = bfs(startX, startY, goalX, goalY);

    // Output the result
    cout << result << endl;

    return 0;
}

提出情報

ジャッジ結果