poj 2386 Lake Counting

#include <ctime>
#include <stdio.h>
#include <iostream>
using namespace std;
int M,N;
char field [102][102] ;
int num = 0;
bool dfs(int x, int y)
{
    field[x][y] = '.';
    for(int i = -1; i <=1; i++)
    {
        for(int j = -1; j <=1; j++)
        {
            int xnext = x + i;
            int ynext = y + j;
            if(xnext >=0 && xnext <N && ynext >=0 && ynext <M && field[xnext][ynext] == 'W')
            {
                dfs(xnext,ynext);
            }
        }
    }
    return true;
}

int main()
{
    std::ios::sync_with_stdio(false);
    scanf("%d%d",&N,&M);
    for(int i = 0; i < N; i++)
    {
        /*
        for(int j = 0; j < M; j++)
        {
            scanf("%c",field[i][j]);
        }
        getchar();*/
        //gets(field[i]);
        cin>>field[i];
    }
    for(int i = 0; i < N; i++)
    {
        for(int j = 0; j < M; j++)
        {
            if(field[i][j]=='W')
            {
                dfs(i,j);
                num++;
                /*for(int v = 0;v< N;v++)
                {
                    for(int b = 0;b< M;b++)
                    {
                        printf("%c",field[v][b]);
                    }
                    printf("\n");
                }printf("________________________\n\n");*/
            }

        }
    }
    printf("%d\n",num);
    return 0;
}