Sokkelo

#include <iostream>
#include <vector>
#include <set>

using namespace std;

char kartta[1010][1010]{};

void paasy(vector<pair<int, int>> &p, int n, int m, int y, int x)
{
    if (kartta[y][x] == '#')
        return;

    p.push_back({y, x});
    kartta[y][x] = '#';

    paasy(p, n, m, y + 1, x);
    paasy(p, n, m, y - 1, x);
    paasy(p, n, m, y, x - 1);
    paasy(p, n, m, y, x + 1);
};

int main()
{
    int n, m;
    cin >> n >> m;

    pair<int, int> A;
    pair<int, int> B;

    for (int i = 0; i < n; i++)
        for (int j = 0; j < m; j++)
        {
            cin >> kartta[i][j];
            if (kartta[i][j] == 'A')
                A = {i, j};
            if (kartta[i][j] == 'B')
                B = {i, j};
        }

    vector<pair<int, int>> An;
    paasy(An, n, m, A.first, A.second);

    vector<pair<int, int>> Bn;
    Bn.push_back(B);
    paasy(Bn, n, m, B.first, B.second);

    int tulos = 1e9;

    for (pair<int, int> a : An)
        for (pair<int, int> b : Bn)
            tulos = min(tulos, abs(a.first - b.first) + abs(a.second - b.second));

    cout << max(tulos, 1);
}

Test 1

Group: 1, 2

Verdict: ACCEPTED

Test 2

Group: 1, 2

Verdict: ACCEPTED

Test 3

Group: 1, 2

Verdict: ACCEPTED

Test 4

Group: 2

Verdict: ACCEPTED

Test 5

Group: 2

Verdict: TIME LIMIT EXCEEDED

Test 6

Group: 2

Verdict: TIME LIMIT EXCEEDED

Test 7

Group: 1, 2

Verdict: ACCEPTED

Test 8

Group: 2

Verdict: TIME LIMIT EXCEEDED

Test 9

Group: 2

Verdict: TIME LIMIT EXCEEDED

Test 10

Group: 1, 2

Verdict: ACCEPTED

Test 11

Group: 2

Verdict: TIME LIMIT EXCEEDED

Test 12

Group: 1, 2

Verdict: ACCEPTED

Test 13

Group: 2

Verdict: ACCEPTED

Test 14

Group: 1, 2

Verdict: ACCEPTED

Test 15

Group: 2

Verdict: ACCEPTED

Test 16

Group: 2

Verdict: ACCEPTED

Test 17

Group: 2

Verdict: ACCEPTED