lake counting (dfs)

#include<stdio.h>
#include<stdlib.h>
int N, M;
char field[3][3] =
{
    { 'W','*','*'},
    { '*','W','*'},
    { '*','*','*'},
};
void dfs(int x,int y) {
    field[x][y] = '*';
    
    for (int dx = -1; dx <= 1; dx++){
        for (int dy = -1; dy <= 1; dy++) {
            int nx = x + dx, ny = y + dy;
            if (0 <= nx && nx < N && 0 <= ny && ny < M&&field[nx][ny] == 'W')
                dfs(nx, ny);
        }
    }
    return;
}

void solve() {
    int res = 0;
    for (int i = 0; i < N; i++) {
        for (int j = 0; j < M; j++) {
            if (field[i][j] == 'W') {
                dfs(i, j);
                res++;
            }
        }
    }
    printf("%d", res);    
}

int main() {
    scanf("%d%d", &N,&M);
    solve();
   // system("pause");
    return 0;
}

从任意w 开始 不停地把临接部分用“*”代替

直到图中不再存在W