Abandoned warehouse

input/code.cpp: In function 'int main()':
input/code.cpp:92:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   92 |     for (int i = 0; i < steps.size(); i++) cout << steps[i];
      |                     ~~^~~~~~~~~~~~~~
input/code.cpp:68:21: warning: 'endi' may be used uninitialized [-Wmaybe-uninitialized]
   68 |     if (mindist[endi][endj] == inf) {
      |                     ^
input/code.cpp:13:9: note: 'endi' was declared here
   13 |     int endi;
      |         ^~~~
input/code.cpp:68:27: warning: 'endj' may be used uninitialized [-Wmaybe-uninitialized]
   68 |     if (mindist[endi][endj] == inf) {
      |                           ^
input/code.cpp:14:9: note: 'endj' was declared here
   14 |     int endj;
      |         ^~~~
In file included from /usr/include/c++/13/bits/uses_allocator_args.h:38,
                 from /usr/include/c++/13/bits/memory_resource.h:41,...

#include <bits/stdc++.h>

using namespace std;
#define ll long long

int main() {

    int n, m;
    cin >> n >> m;

    int starti;
    int startj;
    int endi;
    int endj;

    vector<vector<int>> grid(n, vector<int>(m, -1));
    for (int i = 0; i < n; i++) {
        string s;
        cin >> s;
        for (int j = 0; j < m; j++) {
            if (s[j] == 'A') {
                starti = i;
                startj = j;
                grid[i][j] = 0;
            } else if (s[j] == 'B') {
                endi = i;
                endj = j;
                grid[i][j] = 0;
            } else {
                grid[i][j] = s[j] == '#' ? 1 : 0;
            }
        }
    }

    // distance, i, j
    queue<tuple<int, int, int, int, int>> q;
    q.push(make_tuple(0, starti, startj, -1, -1));

    int inf = 1'000'000'000;
    vector<vector<int>> mindist(n, vector<int>(m, inf));
    vector<vector<pair<int, int>>> coming(n, vector<pair<int, int>>(m));

    while (!q.empty()) {
    
        auto [d, i, j, fi, fj] = q.front();
        q.pop();
        if (d >= mindist[i][j]) continue;
    
        mindist[i][j] = d;
        coming[i][j] = make_pair(fi, fj);

        vector<pair<int, int>> v = {{0, 1}, {0, -1}, {1, 0}, {-1, 0}};

        for (auto &[di, dj] : v) {

            int ni = i+di;
            int nj = j+dj;

            if (ni < 0 || ni >= n || nj < 0 || nj >= m) continue;
            if (grid[ni][nj] == 1) continue;

            q.push(make_tuple(d+1, ni, nj, i, j));

        }

    }

    if (mindist[endi][endj] == inf) {
        cout << "NO" << endl;
        return 0;
    }

    vector<char> steps;
    map<pair<int, int>, char> ma;
    ma[make_pair(0, 1)] = 'R';
    ma[make_pair(1, 0)] = 'D';
    ma[make_pair(-1, 0)] = 'U';
    ma[make_pair(0, -1)] = 'L';

    int ci = endi;
    int cj = endj;
    while (ci != starti || cj != startj) {
        auto [fi, fj] = coming[ci][cj];
        steps.push_back(ma[make_pair(ci-fi, cj-fj)]);
        ci = fi; cj = fj;
    }

    cout << "YES" << endl;
    cout << steps.size() << endl;
    reverse(steps.begin(), steps.end());

    for (int i = 0; i < steps.size(); i++) cout << steps[i];
    cout << 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