Abandoned warehouse

#include <iostream>
#include <vector>
#include <queue>
#include <string>

using namespace std;

struct Position {
    int x, y;
    string path;
};

bool isValid(int x, int y, int n, int m, vector<string>& warehouse, vector<vector<bool>>& visited) {
    return x >= 0 && x < n && y >= 0 && y < m && warehouse[x][y] != '#' && !visited[x][y];
}

int main() {
    int n, m;
    cin >> n >> m;
    vector<string> warehouse(n);
    pair<int, int> start, end;

    for (int i = 0; i < n; ++i) {
        cin >> warehouse[i];
        for (int j = 0; j < m; ++j) {
            if (warehouse[i][j] == 'A') {
                start = {i, j};
            } else if (warehouse[i][j] == 'B') {
                end = {i, j};
            }
        }
    }

    vector<vector<bool>> visited(n, vector<bool>(m, false));
    queue<Position> q;
    q.push({start.first, start.second, ""});
    visited[start.first][start.second] = true;

    int directions[4][2] = {{-1, 0}, {1, 0}, {0, -1}, {0, 1}};
    char moves[4] = {'U', 'D', 'L', 'R'};

    while (!q.empty()) {
        Position current = q.front();
        q.pop();

        if (current.x == end.first && current.y == end.second) {
            cout << "YES" << endl;
            cout << current.path.length() << endl;
            cout << current.path << endl;
            return 0;
        }

        for (int i = 0; i < 4; ++i) {
            int newX = current.x + directions[i][0];
            int newY = current.y + directions[i][1];
            if (isValid(newX, newY, n, m, warehouse, visited)) {
                visited[newX][newY] = true;
                q.push({newX, newY, current.path + moves[i]});
            }
        }
    }

    cout << "NO" << endl;
    return 0;
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: ACCEPTED

Test 12

Verdict: ACCEPTED

Test 13

Verdict: TIME LIMIT EXCEEDED

Test 14

Verdict: ACCEPTED

Test 15

Verdict: ACCEPTED

Test 16

Verdict: ACCEPTED