PROG-1161: Sewer

#include <bits/stdc++.h>
using namespace std;
const int INF=1e9;
using pii=pair<int,int>;
int n,m;
vector <int> g[10001];
vector <int> dis(100001,INF);
bool pst(int i,int j) {
    return i>=1 and i<=n and j>=1 and j<=m;
}
int drt(int i,int j){
    return m*(i-1)+j;
}
int I(int v){
    if(v%m!=0) return v/m+1;
    else return v/m;
}
int J(int v){
    v=v%m;
    if(v==0) return m;
    return v;
}
int main(){
    scanf("%d%d",&n,&m);

    for(int i=1;i<=n;i++){
        for(int j=1;j<=m;j++){
            char a;
            int u,v;
            scanf(" %c",&a);
            u=drt(i,j);
            if(( a=='R' or a=='B' ) and pst(i,j+1)) {
                v=drt(i,j+1);
                g[u].push_back(v);
                g[v].push_back(u);
            }
            if(( a=='D' or a=='B') and pst(i+1,j)) {
                v=drt(i+1,j);
                g[u].push_back(v);
                g[v].push_back(u);
            }
        }
    }

    priority_queue <pii,vector<pii>,greater<pii>> pq;
    dis[1]=1;
    pq.push({1,1});
    while(pq.size()>0){
        int u,d;
        d=pq.top().first;
        u=pq.top().second;
        pq.pop();

        for(auto v:g[u]){
            if(d+1<dis[v]){
                dis[v]=d+1;
                pq.push({d+1,v});
            }
            else if(dis[v]==d+1){
                printf("%d\n%d %d",d+1,I(v),J(v));
                return 0;
            }
        }

    }

    return 0;
}
/*
3 3
B R D
D B N
R N N
*/