Flood fill模板
#include<map>
#include<set>
#include<stack>
#include<cmath>
#include<queue>
#include<string>
#include<bitset>
#include<cstring>
#include<iostream>
#include<algorithm>
#include<numeric>
#include<iomanip>
#define endl '\n'
#define x first
#define y second
using namespace std;
typedef long long ll;
typedef pair<int, int>PII;
const int N=3e5+10;
const int MOD=9901;
const int INF=0X3F3F3F3F;
const int dx[]={-1,1,0,0,-1,-1,+1,+1};
const int dy[]={0,0,-1,1,-1,+1,-1,+1};
const int M = 1e6 + 10;
//flood fill 算法
int n, m;
char g[110][110];
vector<PII>v[N];
int st[110][110];
//相当于记录坐标
void dfs(int i, int j, int o)
{
if(i < 1 || i > n || j < 1 || j > m || st[i][j] || g[i][j] != 'B') return ;
st[i][j] = 1;
v[o].push_back({i, j});
for(int k = 0; k < 4; k ++)
{
dfs(i + dx[k], j + dy[k], o);
}
}
int main()
{
cin >> n >> m;
for(int i = 1; i <= n ; i ++)
{
for(int j = 1; j <= m; j ++)
{
cin >> g[i][j];
}
}
int o = 0;
for(int i = 1; i <= n; i ++)
{
for(int j = 1; j <= m; j ++)
{
if(st[i][j]) continue;
if(g[i][j] == 'B')
{
dfs(i, j, o);
o ++;
}
}
}
int minn = INF;
for(auto p: v[0])
{
for(auto q : v[1])
{
minn = min(minn, abs(p.first - q.first) + abs(p.second - q.second) - 1);
}
}
cout << minn << endl;
return 0;
}