Three States cf-590C

#include <bits/stdc++.h>
using namespace std;
int d[4][1005][1005];
char s[1005][1005];
typedef pair <int, int> pii;
int n, m;
const int inf = 1e8;
const int dx[] = {0, 0, 1, -1};
const int dy[] = {1, -1, 0, 0};

void bfs(int col) {
    queue <pii> Q;
    for(int i = 0; i < n; i++) {
        for(int j = 0; j < m; j++) {
            if(s[i][j] == col + '0') {
                Q.push(pii(i, j));
                d[col][i][j] = 0;
            }
        }
    }

    while(!Q.empty()) {
        int x = Q.front().first;
        int y = Q.front().second;
        Q.pop();
        for(int i = 0; i < 4; i++) {
            int p = x + dx[i];
            int q = y + dy[i];
            if(0 <= p && p < n) {
                if(0 <= q && q < m) {
                    if(s[p][q] != '#' && d[col][p][q] == -1) {
                        d[col][p][q] = 1 + d[col][x][y];
                        Q.push(pii(p, q));
                    }
                }
            }
        }
    }
}

int dist(int c1, int c2) {
    int ans = inf;
    for(int i = 0; i < n; i++) {
        for(int j = 0; j < m; j++) {
            if(s[i][j] == c2 + '0' && d[c1][i][j] != -1) {
                ans = min(ans, d[c1][i][j] - 1);
            }
        }
    }
    return ans;
}
int main (int argc, char const* argv[])
{
    memset(d, -1, sizeof d);
    scanf("%d %d", &n, &m);
    for(int i = 0; i < n; i++) {
        scanf("%s", s[i]);
    }

    bfs(1);
    bfs(2);
    bfs(3);

    int ans = inf;
    ans = min(ans, dist(1, 2) + dist(2, 3));
    ans = min(ans, dist(1, 2) + dist(1, 3));
    ans = min(ans, dist(1, 3) + dist(2, 3));

    for(int i = 0; i < n; i++) {
        for(int j = 0; j < m; j++) {
            if(s[i][j] == '.' && d[1][i][j] != -1 && d[2][i][j] != -1 && d[3][i][j] != -1) {
                ans = min(ans, d[1][i][j] + d[2][i][j] + d[3][i][j] - 2);
            }
        }
    }
    if(ans >= inf) ans = -1;
    printf("%d\n", ans);
    return 0;
}