Abandoned warehouse

input/code.cpp: In function 'bool canVisit(std::pair<int, int>, const std::vector<std::vector<char> >&, const std::vector<std::vector<bool> >&)':
input/code.cpp:15:46: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::vector<char> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   15 |     return coords.first >= 0 && coords.first < labyrinth.size() && coords.second >= 0 && coords.second < labyrinth[0].size() &&
      |                                 ~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~
input/code.cpp:15:104: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   15 |     return coords.first >= 0 && coords.first < labyrinth.size() && coords.second >= 0 && coords.second < labyrinth[0].size() &&
      |                                                                                          ~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~

#include <iostream>
#include <vector>
#include <queue>
#include <string>
#include <algorithm>

using namespace std;

const int dx[4] = {-1, 1, 0, 0};
const int dy[4] = {0, 0, -1, 1};
const char dir_char[4] = { 'U', 'D', 'L', 'R' };

bool canVisit(pair<int, int> coords, const vector<vector<char>>& labyrinth, const vector<vector<bool>>& vis)
{
    return coords.first >= 0 && coords.first < labyrinth.size() && coords.second >= 0 && coords.second < labyrinth[0].size() &&
        !vis[coords.first][coords.second] && labyrinth[coords.first][coords.second] != '#';
}
int main()
{
    int n, m;
    cin >> n >> m;
    vector<vector<char>> labyrinth(n, vector<char>(m));
    int startX, startY;
    int endX, endY;
    startX = startY = endX = endY = -1;
    for (int i = 0; i < n; i++)
    {
        for (int j = 0; j < m; j++)
        {
            cin >> labyrinth[i][j];
            if (labyrinth[i][j] == 'A')
            {
                startX = i;
                startY = j;
            }
            if (labyrinth[i][j] == 'B')
            {
                endX = i;
                endY = j;
            }
            
        }
    }
    vector<vector<bool>> vis(n, vector<bool>(m, false));
    vector<vector<char>> parent(n, vector<char>(m));
    bool found = false;
    queue<pair<int, int>> q;
    q.push(make_pair(startX, startY));
    vis[startX][startY] = true;
    while (!q.empty())
    {
        pair<int, int> point = q.front(); q.pop();
        if (point.first == endX && point.second == endY)
        {
            found = true;
            break;
        }
        for (int i = 0; i < 4; i++)
        {
            pair<int, int> newPoint = point;
            newPoint.first += dx[i];
            newPoint.second += dy[i];
            if (canVisit(newPoint, labyrinth, vis))
            {
                vis[newPoint.first][newPoint.second] = true;
                parent[newPoint.first][newPoint.second] = dir_char[i];
                q.push(newPoint);
            }
        }

    }
    if (found)
    {
        string path = "";
        pair<int, int> point = make_pair(endX, endY);
        while (point.first != startX || point.second != startY)
        {
            char step = parent[point.first][point.second];
            path += step;
            if (step == 'U')
            {
                point.first++;
            }
            else if (step == 'D')
            {
                point.first--;
            }
            else if (step == 'L')
            {
                point.second++;
            }
            else if (step == 'R')
            {
                point.second--;
            }
        }
        std::reverse(path.begin(), path.end());
        cout << "YES" << endl;
        cout << path.length() << endl;
        cout << path << endl;
    }
    else
    {
        cout << "NO" << endl;
    }
}

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