Yeah I have done that. All cases have been accepted except for one which is giving TLE.

I havent used maps , I have only used 2-D arrays

include "bits/stdc++.h"

using namespace std;

define ll long long

int main() { ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0); ll n, m; cin >> n >> m; vector<vector> arr(n, vector(m)); ll b = -1, c = -1; queue<pair<ll, ll>> q; vector<vector> visited(n, vector(m, false));

for (ll i = 0; i < n; i++)
{
    for (ll j = 0; j < m; j++)
    {
        cin >> arr[i][j];
        if (arr[i][j] == 'A')
        {
            b = i;
            c = j;
        }
        else if (arr[i][j] == 'M')
        {
            q.push({i, j});
            visited[i][j] = true;
        }
    }
}

vector<vector<ll>> time(n, vector<ll>(m, INT_MAX));
ll steps = 0;
while (!q.empty())
{
    ll sz = q.size();
    while (sz--)
    {
        auto front = q.front();
        q.pop();
        ll x = front.first, y = front.second;
        time[x][y] = steps;

        if (x + 1 < n and !visited[x + 1][y] and arr[x + 1][y] == '.')
        {
            visited[x + 1][y] = true;
            q.push({x + 1, y});
        }
        if (x - 1 >= 0 and !visited[x - 1][y] and arr[x - 1][y] == '.')
        {
            visited[x - 1][y] = true;
            q.push({x - 1, y});
        }
        if (y + 1 < m and !visited[x][y + 1] and arr[x][y + 1] == '.')
        {
            visited[x][y + 1] = true;
            q.push({x, y + 1});
        }
        if (y - 1 >= 0 and !visited[x][y - 1] and arr[x][y - 1] == '.')
        {
            visited[x][y - 1] = true;
            q.push({x, y - 1});
        }
    }
    ++steps;
}

// for (auto x : time)
// {
//     for (auto y : x)
//         cout << y << " ";
//     cout << endl;
// }

for (ll i = 0; i < n; i++)
{
    for (ll j = 0; j < m; j++)
        visited[i][j] = false;
}

queue<pair<string, pair<ll, ll>>> pq;
pq.push({"", {b, c}});
visited[b][c] = true;
steps = 0;
while (!pq.empty())
{
    ll sz = pq.size();
    while (sz--)
    {
        auto front = pq.front();
        pq.pop();
        string res = front.first;
        ll x = front.second.first, y = front.second.second;
        // cout << x << " " << y << endl;
        visited[x][y] = true;

        if (x == 0 or x == n - 1 or y == 0 or y == m - 1)
        {
            // cout << x << " " << y << endl;
            cout << "YES" << endl;
            cout << steps << endl
                 << res;
            return 0;
        }

        if (x + 1 < n and !visited[x + 1][y] and arr[x + 1][y] == '.' and steps + 1 < time[x + 1][y])
        {
            visited[x + 1][y] = true;
            pq.push({res + 'D', {x + 1, y}});
        }
        if (x - 1 >= 0 and !visited[x - 1][y] and arr[x - 1][y] == '.' and steps + 1 < time[x - 1][y])
        {
            visited[x - 1][y] = true;
            pq.push({res + 'U', {x - 1, y}});
        }
        if (y + 1 < m and !visited[x][y + 1] and arr[x][y + 1] == '.' and steps + 1 < time[x][y + 1])
        {
            visited[x][y + 1] = true;
            pq.push({res + 'R', {x, y + 1}});
        }
        if (y - 1 >= 0 and !visited[x][y - 1] and arr[x][y - 1] == '.' and steps + 1 < time[x][y - 1])
        {
            visited[x][y - 1] = true;
            pq.push({res + 'L', {x, y - 1}});
        }
    }
    ++steps;
}
cout << "NO";

return 0;

}