Shared code

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
using namespace std;
#define ll long long
const ll mod = 1e9 + 7;
// Using a pair<int, int> to handle duplicates in pbds
// typedef tree<pair<ll, int>, null_type, less<pair<ll, int>>, rb_tree_tag, tree_order_statistics_node_update> pbds;
typedef tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update> pbds; // find_by_order, order_of_key

vector<pair<char, pair<int, int>>> direction = {
    {'D', {1, 0}},  
    {'U', {-1, 0}}, 
    {'L', {0, -1}}, 
    {'R', {0, 1}}   
};

void bfs(vector<vector<char>> &grid, int i, int j, string &path)
{
    int n = grid.size(), m = grid[0].size();

    
    queue<pair<pair<int, int>, string>> q;
    q.push({{i, j}, ""}); 

    while (!q.empty())
    {

        auto fr = q.front();
        int ii = fr.first.first, jj = fr.first.second;
        string currPath = fr.second;
        q.pop();

        if (grid[ii][jj] == 'B')
        {
            path = currPath; 
            return;          
        }

        grid[ii][jj] = '#';

        for (auto &dir : direction)
        {
            int iii = ii + dir.second.first;
            int jjj = jj + dir.second.second;
            char d = dir.first;

            if (iii >= 0 && iii < n && jjj >= 0 && jjj < m && grid[iii][jjj] != '#')
            {
                q.push({{iii, jjj}, currPath + d});
            }
        }
    }
}

void solve()
{
    int n, m;
    cin >> n >> m;

    vector<vector<char>> grid(n, vector<char>(m));
    for (int i = 0; i < n; i++)
    {
        for (int j = 0; j < m; j++)
            cin >> grid[i][j];
    }

    string ans;
    int ii,jj;

    for (int i = 0; i < n; i++)
    {
        for (int j = 0; j < m; j++)
        {
            if (grid[i][j] == 'A')
            {
                ii=i; jj=j;
                break;
            }
        }
    }

    bfs(grid,ii,jj,ans);

    if (ans.empty())
    {
        cout << "NO" << endl;
    }
    else
    {
        cout << "YES" << endl;
        cout << ans.size() << endl;
        cout << ans << endl;
    }
}

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);

    solve();
}