Abandoned warehouse

input/code.cpp: In function 'void Test()':
input/code.cpp:69:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   69 |     freopen("temp\\in.txt", "r", stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~
input/code.cpp: In function 'int main()':
input/code.cpp:74:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   74 |     scanf("%d%d", &n, &m);
      |     ~~~~~^~~~~~~~~~~~~~~~

#include<iostream>
#include<cstdio>
#include<queue>
#include<string>
#include<stack>
typedef long long LL;
typedef std::pair<int,int> poi;

const int N=1005;
using namespace std;

int des[4][2]={{-1,0},{0,1},{1,0},{0,-1}}; 
// U R L D
char reverse_des[4]={'U', 'R', 'D', 'L'};
int n, m, dis[N][N], parent[N][N];
poi start_poi, end_poi;
bool map[N][N], vis[N][N];

bool Check(int x, int y)
{
    if(x < 1 || x > n || y < 1 || y > m)
        return false;
    if(vis[x][y] || map[x][y])
        return false;
    return true;
}

bool BFS()
{
    std::queue<poi> q;

    // Start point
    int u = start_poi.first, v = start_poi.second;
    vis[u][v] = true;
    dis[u][v] = 0;
    q.push(start_poi);

    while(!q.empty())
    {
        poi p = q.front();
        q.pop();
        //Check
        if(p == end_poi)
            break;
        //Expand
        int u = p.first, v = p.second;
        for(int i=0; i<4; i++)
        {
            int x = u+des[i][0], y = v+des[i][1];
            if(Check(x, y))
            {
                vis[x][y] = true;
                dis[x][y] = dis[u][v] + 1;
                parent[x][y] = i;
                q.push(std::make_pair(x, y));
            }
        }
    }
    
    if(vis[end_poi.first][end_poi.second])
        return true;
    else
        return false;
}


void Test()
{
    freopen("temp\\in.txt", "r", stdin);
}
int main()
{
    // Test();
    scanf("%d%d", &n, &m);
    getchar();
    for(int i=1; i<=n; i++)
    {
        std::string s;
        std::getline(std::cin, s);

        for(int j=1; j<=m; j++)
        {
            if(s[j-1] == '#')
                map[i][j] = 1;
            if(s[j-1] == 'A')
                start_poi = std::make_pair(i, j);
            if(s[j-1] == 'B')
                end_poi = std::make_pair(i, j);
        }
    }
    if(BFS())
    {
        printf("YES\n");
        printf("%d\n", dis[end_poi.first][end_poi.second]);

        std::stack<char> ans;
        poi now = end_poi;
        while(now != start_poi)
        {
            int way = parent[now.first][now.second];
            ans.push(reverse_des[way]);
            now.first-=des[way][0];
            now.second-=des[way][1];
        }

        while(!ans.empty())
        {
            char c = ans.top();
            ans.pop();
            putchar(c);
        }
    } else {
        printf("NO");
    }
        

    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