Shared code

#include <bits/stdc++.h>

using namespace std;

struct obj{
	int i;
	int j;
	string s;
	obj* o;
	obj(int,int,string,obj*);
};

obj::obj(int _i,int _j, string _s, obj* _o){
	this->i = _i;
	this->j = _j;
	this->s = _s;
	this->o = _o;
}

bool check(int x, int y, int n, int m, vector<vector<int>> const &lab, vector<vector<int>> &seen){
	if(x >= 0 && y >= 0 && x < n && y < m && lab[x][y] && !seen[x][y]){
		seen[x][y] = 1;
		return true;
	}
	return false;
}

int main(){
	int n,m; cin >> n >> m;
	
	pair<int,int> A,B;
	vector<vector<int>> lab(n,vector<int>(m,0));
	
	for(int i=0;i<n;i++){
		string s; cin >> s;
		for(int j=0;j<s.size();j++){
			if(s[j] == 'A'){
				A.first = i; A.second = j;
			}
			else if(s[j] == 'B'){
				B.first = i; B.second = j;
				lab[i][j] = 2;
			}
			else if(s[j] == '.'){
				lab[i][j] = 1;
			}
		}
	}
	
	queue<obj*> q;
	obj *test = new obj(A.first,A.second,"",nullptr);
	q.push(test);
	
	vector<vector<int>> seen(n,vector<int>(m,0));
	while(!q.empty()){
		auto x = q.front();
		q.pop();
		
		if(lab[x->i][x->j] == 2){
			cout << "YES" << endl;
			int total = 0;
			vector<string> f;
			for(obj* w=x;w->o != nullptr;w=w->o){
				total++;
				f.push_back(w->s);
			}
			cout << total << "\n";
			for(int i=f.size()-1;i>=0;i--){
				cout << f[i];
			}
			cout << endl;
			return 0;
		}
		
		if(check(x->i-1,x->j,n,m,lab,seen)){
			obj *test = new obj(x->i-1,x->j,"U",x);
			q.push(test);
		}
		if(check(x->i+1,x->j,n,m,lab,seen)){
			obj *test = new obj(x->i+1,x->j,"D",x);
			q.push(test);
		}
		if(check(x->i,x->j-1,n,m,lab,seen)){
			obj *test = new obj(x->i,x->j-1,"L",x);
			q.push(test);
		}
		if(check(x->i,x->j+1,n,m,lab,seen)){
			obj *test = new obj(x->i,x->j+1,"R",x);
			q.push(test);
		}
	}
	
	cout << "NO" << endl;
	
	return 0;
}