Abandoned warehouse

#include <bits/stdc++.h>
using namespace std;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int n, m;
    cin >> n >> m;
    vector<string> a(n);
    for (int i = 0; i < n; i++) cin >> a[i];

    pair<int,int> s, t;
    for (int i = 0; i < n; i++)
        for (int j = 0; j < m; j++) {
            if (a[i][j] == 'A') s = {i,j};
            if (a[i][j] == 'B') t = {i,j};
        }

    vector<vector<int>> d(n, vector<int>(m,-1));
    vector<vector<char>> p(n, vector<char>(m));
    queue<pair<int,int>> q;
    q.push(s);
    d[s.first][s.second] = 0;

    int dx[]={-1,1,0,0}, dy[]={0,0,-1,1};
    char dir[]={'U','D','L','R'};

    while (!q.empty()) {
        auto [x,y] = q.front(); q.pop();
        for (int k=0;k<4;k++) {
            int nx=x+dx[k], ny=y+dy[k];
            if(nx<0||nx>=n||ny<0||ny>=m) continue;
            if(a[nx][ny]=='#'||d[nx][ny]!=-1) continue;
            d[nx][ny]=d[x][y]+1;
            p[nx][ny]=dir[k];
            q.push({nx,ny});
        }
    }

    if(d[t.first][t.second]==-1){cout<<"NO\n";return 0;}

    cout<<"YES\n"<<d[t.first][t.second]<<"\n";
    string path;
    for(pair<int,int> cur=t; cur!=s;){
        char c=p[cur.first][cur.second];
        path+=c;
        if(c=='U') cur.first++;
        else if(c=='D') cur.first--;
        else if(c=='L') cur.second++;
        else cur.second--;
    }
    reverse(path.begin(), path.end());
    cout<<path<<"\n";
    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: ACCEPTED

Test 14

Verdict: ACCEPTED

Test 15

Verdict: ACCEPTED

Test 16

Verdict: ACCEPTED