Revise paste Untitled

#include <iostream>
#include <queue>
#include <vector>
using namespace std;

int n, m;
char mat[105][105];

int bfs(int si, int sj, int ei, int ej) {
    queue<int> q;
    q.push(si);
    q.push(sj);
    q.push(0);
    
    vector<vector<bool>> visited(n, vector<bool>(m, false));

int di[] = {-1, 1, 0, 0};
    int dj[] = {0, 0, -1, 1};

while(!q.empty()) {
        int ci = q.front();
        q.pop();
        int cj = q.front();
        q.pop();
        int dist = q.front();
        q.pop();
        
        if(ci == ei and cj == ej) {
            return dist;
        }
        for(int i = 0; i < 4; i++) {
            int ti = ci + di[i];
            int tj = cj + dj[i];

if(ti >= 0 and ti < n and tj >= 0 and tj < m and mat[ti][tj] != '#' and !visited[ti][tj]) {
                q.push(ti);
                q.push(tj);
                q.push(dist + 1);
                visited[ti][tj] = true;
            }
        }
        
    }
    return 1e8;
}
int main() {
    cin >> n >> m;
    vector<pair<int, int>> d;
    int drinks = 0;
    int si, sj, ei, ej;
    for(int i = 0; i < n; i++) {
        for(int j = 0; j < m; j++) {
            cin >> mat[i][j];
            
            if(mat[i][j] == 'S') {
                si = i;
                sj = j;
            }
            if(mat[i][j] == 'B') {
                ei = i;
                ej = j;
            }
            if(mat[i][j] == 'D') {
                d.push_back(make_pair(i, j));
                drinks++;
            }
        }
    }
    int res = 2e9;
    if(drinks == 1) {
        res = bfs(si, sj, d[0].first, d[0].second) + bfs(d[0].first, d[0].second, ei, ej);
    }
    else if(drinks == 2) {
        int r1 = bfs(si, sj, d[0].first, d[0].second) + bfs(d[0].first, d[0].second, d[1].first, d[1].second) + bfs(d[1].first, d[1].second, ei, ej);
        int r2 = bfs(si, sj, d[1].first, d[1].second) + bfs(d[1].first, d[1].second, d[0].first, d[0].second) + bfs(d[0].first, d[0].second, ei, ej);
        res = min(r1, r2);
    }
    else {
        int r1 = bfs(si, sj, d[0].first, d[0].second) + bfs(d[0].first, d[0].second, d[1].first, d[1].second) + bfs(d[1].first, d[1].second, d[2].first, d[2].second) + bfs(d[2].first, d[2].second, ei, ej);
        int r2 = bfs(si, sj, d[0].first, d[0].second) + bfs(d[0].first, d[0].second, d[2].first, d[2].second) + bfs(d[2].first, d[2].second, d[1].first, d[1].second) + bfs(d[1].first, d[1].second, ei, ej);
        int r3 = bfs(si, sj, d[1].first, d[1].second) + bfs(d[1].first, d[1].second, d[0].first, d[0].second) + bfs(d[0].first, d[0].second, d[2].first, d[2].second) + bfs(d[2].first, d[2].second, ei, ej);
        int r4 = bfs(si, sj, d[1].first, d[1].second) + bfs(d[1].first, d[1].second, d[2].first, d[2].second) + bfs(d[2].first, d[2].second, d[0].first, d[0].second) + bfs(d[0].first, d[0].second, ei, ej);
        int r5 = bfs(si, sj, d[2].first, d[2].second) + bfs(d[2].first, d[2].second, d[0].first, d[0].second) + bfs(d[0].first, d[0].second, d[1].first, d[1].second) + bfs(d[1].first, d[1].second, ei, ej);
        int r6 = bfs(si, sj, d[2].first, d[2].second) + bfs(d[2].first, d[2].second, d[1].first, d[1].second) + bfs(d[1].first, d[1].second, d[0].first, d[0].second) + bfs(d[0].first, d[0].second, ei, ej);
        res = min(min(r1, r2), min(r3, r4));
        res = min(res, min(r5, r6));

}
    if(res > 1e8) {
        res = -1;
    }
    cout << res << endl;
    return 0;
}

/*
5 6
#S.###
#...##
.#..##
D..B#.
##.#..
 
 **/