C++ :

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>

using namespace std;
int a[100][100],ans,m,n;
const int dx[]={0,0,1,-1},dy[]={1,-1,0,0};
struct queh
{
	int x,y;
}que[100*100];
void init()
{
	cin>>m>>n;
	
	for(int i=1;i<=m;i++)
	{
		for(int j=1;j<=n;j++)
			scanf("%1d",&a[i][j]);
	}
}
void bfs(int x,int y)
{
	int head=0,tail=1;
	que[head].x=x,que[head].y=y;
	a[x][y]=0;
	while(head!=tail)
	{
		for(int i=0;i<4;i++)
		{
			int nx=que[head].x+dx[i],ny=que[head].y+dy[i];
			if(a[nx][ny]&&nx>0&&ny>0&&nx<=m&&ny<=n)
			{
				//add(nx,ny);
				queh t;
				t.x=nx,t.y=ny;
				que[tail++]=t;
				a[nx][ny]=0;
			}
		}
		head++;
	}
}
void print()
{
	printf("%d",ans);
}
int main()
{
	init();
	for(int i=1;i<=m;i++)
	for(int j=1;j<=n;j++)
	 if(a[i][j]!=0){
	 	bfs(i,j);
		 ans++;	
	 }
	print();
	return 0;
}

Java :

import java.util.LinkedList;
import java.util.Queue;
import java.util.Scanner;


public class Main {
	static char[][] map;
	static int[][] d;
	static int m,n;
	public static void main(String[] args) {
		Scanner in = new Scanner(System.in);
		while (in.hasNextInt()) {
			m = in.nextInt();
			n = in.nextInt();
			map = new char[m][n];
			d = new int[m][n];
			for (int i = 0; i < m; i++) {
				String s = in.next();
				for (int j = 0; j < n; j++) {
					map[i][j] = s.charAt(j);
				}
			}
			int cnt = 0;
			for(int i=0;i<m;i++){
				for(int j=0;j<n;j++){
					if(map[i][j]!='0'&&d[i][j]==0)	
						dfs(i,j,++cnt);
				}
			}
			System.out.println(cnt);
		}
	}
	public static void dfs(int r,int c,int id){
		if(r<0||r>=m||c<0||c>=n)
			return;
		if(d[r][c]>0 || map[r][c]=='0')
			return;
		d[r][c] = id;
		dfs(r+1,c,id);
		dfs(r-1,c,id);
		dfs(r,c+1,id);
		dfs(r,c-1,id);
	}
}