这题用广度优先搜索

#include <bits/stdc++.h>
using namespace std;
const int N = 120;
int n, m;
int ans = 0;
char a[N][N];
int dx[8] = {-1, -1, -1, 0, 0, 1, 1, 1};
int dy[8] = {-1, 0, 1, -1, 1, -1, 0, 1};
bool vis[N][N];
struct node{
    int x, y;
}l, r;
void bfs(int x, int y){
    queue<node> q;
    q.push({x, y});
    vis[x][y] = 1;
    while(q.size()){
        l = q.front();
        q.pop();
        for(int i = 0; i < 8; i++){
            int nx = l.x + dx[i];
            int ny = l.y + dy[i];
            if(nx >= 1 && ny >= 1 && nx <= n && ny <= m && !vis[nx][ny] && a[nx][ny] == 'W'){
                vis[nx][ny] = 1;
                q.push({nx, ny});
            }
        }
    }
}
int main(){
    cin >> n >> m;
    memset(vis, 0, sizeof vis);
    for(int i = 1; i <= n; i++){
        for(int j = 1; j <= m; j++){
            cin >> a[i][j];
        }
    }
    for(int i = 1; i <= n; i++){
        for(int j = 1; j <= m; j++){
            if(a[i][j] == 'W' && !vis[i][j]){
                bfs(i, j);
                ans++;
            }
        }
    }
    cout << ans;
    return 0;
}