Shared code

//REMEMBERING THE PAST , CAN AVOID REPEAT THE SAME 
#include<bits/stdc++.h>
using namespace std;
#define mod 1000000007
#define inf 10000000000000000
typedef long long ll;
#define mp make_pair
#define f first 
#define s second
// DP o Trees::http://cfrp.azurewebsites.net/blog/entry/20935
ll GCD(ll a,ll b){
    ll maxi=max(a,b);
    ll mini=min(a,b);
    while(maxi && mini){
        ll t=mini;
        mini=maxi%mini;
        maxi=t; 
    }
    return max(maxi,mini);
}
ll power(ll x,ll y){
    ll res=1;
    while (y){
        if (y & 1){
            res=(res*x); 
        }
        x=(x*x);
        y=y>>1;
    }
    return res;
}
ll ncr(ll x, ll y){
 	ll ans=1;
 	y=(y > x-y? x-y: y);
 	for(ll i=0; i<y; i++){
 		ans=(ans*(x-i))%mod;
 		ans=(ans*power(i+1,mod-2))%mod;
 		ans=ans%mod;
 	}
 	return ans;
}
int main(){
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);
	cout.tie(NULL);
	int n,m;
	cin>>n>>m;
	char mat[n][m];
	bool visited[n][m];
	memset(visited,false,sizeof(visited));
	char direction[n][m];
	pair<int,int> start,end;
	for(int i=0;i<n;i++){
		for(int j=0;j<m;j++){
			cin>>mat[i][j];
			if(mat[i][j]=='A'){
				start={i,j};
			}
			else if(mat[i][j]=='B'){
				end={i,j};
			}
		}
	}
	queue<pair<int,int>> q;
	q.push(start);
	visited[start.f][start.s]=true;
	int dx[]={1,-1,0,0};
	int dy[]={0,0,1,-1};
	pair<int,int> parent[n][m];
	map<int,char> dir;
	dir[0]='D';
	dir[1]='U';
	dir[2]='R';
	dir[3]='L';
	bool flag=false;
	while(!q.empty()){
		int x=q.front().f;
		int y=q.front().s;
		q.pop();
		for(int i=0;i<4;i++){
			int tx=x+dx[i],ty=y+dy[i];
			if(tx>=0 && tx<n && ty>=0 && ty<m && !visited[tx][ty] && mat[tx][ty]!='#'){
				visited[tx][ty]=true;
				direction[tx][ty]=dir[i];
				parent[tx][ty]={x,y};
				if(mp(tx,ty)==end){
					flag=true;
					break;
				}
				q.push({tx,ty});
			}
		}
		if(flag){
			break;
		}
	}
	if(flag){
		cout<<"YES\n";
		pair<int,int> son=end;
		char prev;
		string ans="";
		while(son!=start){
			prev=direction[son.f][son.s];
			ans=prev+ans;
			son=parent[son.f][son.s];
		}
		cout<<ans.size()<<"\n";
		cout<<ans<<"\n";
	}
	else{
		cout<<"NO\n";
	}
	return 0;
}