Abandoned warehouse

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

using namespace std;

// Directions: (dx, dy) pairs corresponding to Up, Right, Down, Left
const vector<pair<int, int>> directions = {{-1, 0}, {0, 1}, {1, 0}, {0, -1}};
const vector<char> directionChars = {'U', 'R', 'D', 'L'};

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

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

int main() {
    ios::sync_with_stdio(false);  // Disable synchronization with C I/O for speed
    cin.tie(NULL);  // Untie cin from cout for faster I/O

    int n, m;
    cin >> n >> m;
    
    vector<vector<char>> warehouse(n, vector<char>(m));
    vector<vector<bool>> visited(n, vector<bool>(m, false));
    
    int startX = -1, startY = -1, endX = -1, endY = -1;
    
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < m; j++) {
            cin >> warehouse[i][j];
            if (warehouse[i][j] == 'A') {
                startX = i;
                startY = j;
            }
            if (warehouse[i][j] == 'B') {
                endX = i;
                endY = j;
            }
        }
    }

    // BFS setup
    queue<Node> q;
    q.push({startX, startY, ""});
    visited[startX][startY] = true;
    
    while (!q.empty()) {
        Node current = q.front();
        q.pop();
        
        // Check if we've reached the exit
        if (current.x == endX && current.y == endY) {
            cout << "YES" << endl;
            cout << current.path.length() << endl;
            cout << current.path << endl;
            return 0;
        }
        
        // Explore all 4 directions
        for (int i = 0; i < 4; i++) {
            int newX = current.x + directions[i].first;
            int newY = current.y + directions[i].second;
            
            if (isValid(newX, newY, n, m, warehouse, visited)) {
                visited[newX][newY] = true;
                q.push({newX, newY, current.path + directionChars[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