Go: ///
// File:  1160.go
// Author: ymiyamoto
//
// Created on Sun Mar  4 20:45:57 2018
//
package main

import (
	"fmt"
)

var w, h int
var graph [][]string

func dfs(visited [][]bool, x, y int) {
	visited[x][y] = true

	for i := -1; i <= 1; i++ {
		for j := -1; j <= 1; j++ {
			dx := x + i
			dy := y + j
			if 0 <= dx && dx < h && 0 <= dy && dy < w && graph[dx][dy] == "1" && !visited[dx][dy] {
				dfs(visited, dx, dy)
			}
		}
	}
}

func main() {
	for {
		fmt.Scan(&w, &h)
		if w == 0 && h == 0 {
			break
		}

		graph = make([][]string, h)
		for i := range graph {
			graph[i] = make([]string, w)
		}

		for i := 0; i < h; i++ {
			for j := 0; j < w; j++ {
				var s string
				fmt.Scan(&s)
				graph[i][j] = s
			}
		}

		visited := make([][]bool, h)
		for i := range visited {
			visited[i] = make([]bool, w)
		}

		count := 0
		for i := range graph {
			for j := range graph[i] {
				if graph[i][j] == "1" && !visited[i][j] {
					dfs(visited, i, j)
					count++
				}
			}
		}

		fmt.Println(count)
	}
}

C++: #include<stdio.h>
void printmap();
void draw(int x,int y);
int w,h,c[51][51];

int main(){
	int i,j;
	int count;


	scanf("%d %d",&w,&h);


	while((w!=0)&&(h!=0)){
		count=0;
	
		for(j=0;j<h;j++){
			for(i=0;i<w;i++){
				scanf("%d",&c[j][i]);
			}
		}
		//printf("\n");
		
		for(i=0;i<w;i++){
			c[h][i]=0;
		}
		for(i=0;i<h;i++){
			c[i][w]=0;
		}

		for(i=0;i<w;i++){
			for(j=0;j<h;j++){
				if(c[j][i]==1){
					count++;
					//printf("count up count=%d\n",count);
					draw(j,i);
					printmap();
				}
			}
		}

		printf("%d\n",count);
		scanf("%d %d",&w,&h);
	}
	return 0;
}

void draw(int x,int y){
	printf("delete %d %d\n",x,y);
	int i,j;
	c[x][y]=0;
	for(i=0;i<3;i++){
		for(j=0;j<3;j++){
			if(c[x-1+i][y-1+j]==1){
				draw(x-1+i,y-1+j);
			}
		}
	}


}

void printmap(){
	int i,j;
	for(j=0;j<h;j++){
		for(i=0;i<w;i++){
			printf("%d ",c[j][i]);
		}
		printf("\n");
	}
}

C++: #include <bits/stdc++.h>
#define rep(i,n) for(long long int i = 0; i < n; i++)
#define _rep(i,m,n) for(long long int i = m; i < n; i++)
#define print(n) std::cout << n << std::endl
#define _print(n) std::cout << n
using namespace std;
typedef long long ll;
const int N = 1000000;
const ll mod = 1000000007;
using Graph = vector<vector<int>>;
const int dx[4] = {1, 0, -1, 0};
const int dy[4] = {0, 1, 0, -1};

int H,W;
vector<vector<int>> field;

void dfs(int h, int w){
   field[h][w] = 0;
   
   for(int dh = -1; dh <= 1; dh++){
      for(int dw = -1; dw <= 1; dw++){
         int nh = h + dh;
         int nw = w + dw;
      
         if(nh < 0 || nh >= H || nw < 0 || nw >= W)continue;
         if(field[nh][nw] == 0)continue;

         dfs(nh, nw);
      }
   }
}

int main(){
   while(true){
   cin >> W >> H;
   if(H == 0 || W == 0)return 0;
   field.assign(H, vector<int>(W, 0));

   for (int i = 0; i < H; i++){
      for(int j = 0; j < W; j++){
         cin >> field[i][j];
      }
   }

   int count = 0;
   for(int i = 0; i < H; i++){
      for(int j = 0; j < W; j++){
         if(field[i][j] == 0) continue;
         dfs(i, j);
         count++;
      }
   }
   cout << count << endl;
   }
}

C++: #include <iostream>
#include <queue>
using namespace std;

int w, h, c, n;
int a[50][50];
queue<int> q;

void bfs() {
	int x, y;
	while (1) {
		x = q.front() % w;
		y = q.front() / w;
		
		if ( x > 0 && y > 0 && a[y - 1][x - 1] == 1 ) {
			a[y - 1][x - 1] = 0;
			q.push( ( y - 1 ) * w + x - 1 );
		}
		if ( x < w - 1 && y > 0 && a[y - 1][x + 1] == 1 ) {
			a[y - 1][x + 1] = 0;
			q.push( ( y - 1 ) * w + x + 1 );
		}
		if ( x > 0 && y < h - 1 && a[y + 1][x - 1] == 1 ) {
			a[y + 1][x - 1] = 0;
			q.push( ( y + 1 ) * w + x - 1 );
		}
		if ( x < w - 1 && y < h - 1 && a[y + 1][x + 1] == 1 ) {
			a[y + 1][x + 1] = 0;
			q.push( ( y + 1 ) * w + x + 1 );
		}
		if ( x > 0 && a[y][x - 1] == 1 ) {
			a[y][x - 1] = 0;
			q.push( y * w + x - 1 );
		}
		if ( y > 0 && a[y - 1][x] == 1 ) {
			a[y - 1][x] = 0;
			q.push( ( y - 1 ) * w + x );
		}
		if ( x < w - 1 && a[y][x + 1] == 1 ) {
			a[y][x + 1] = 0;
				q.push( y * w + x + 1 );
		}
		if ( y < h - 1 && a[y + 1][x] == 1 ) {
			a[y + 1][x] = 0;
			q.push( ( y + 1 ) * w + x );
		}
		q.pop();
		if ( q.empty() ) break;	
	}
	n++;
}

int main() {

	while (1) {
		n = 0;
		for ( int j = 0; j < 50; j++ )
			for ( int i = 0; i < 50; i++ )
				a[j][i] = 0;
		cin >> w >> h;
		if ( w == 0 ) break;
		for ( int j = 0; j < h; j++ ) {
			for ( int i = 0; i < w; i++ ) {
				cin >> c;
				a[j][i] = c;
			}
		}
		for ( int j = 0; j < h; j++ ) {
			for ( int i = 0; i < w; i++ ) {
				if ( a[j][i] == 1 ) {
					a[j][i] = 0;
					q.push( j * w + i );
					bfs();
				}
			}
		}
		cout << n << endl;
	}
}

C++: #include<iostream>
#include<vector> 
#include<queue>
using namespace std;

int x,y;
int ti[51][51];
const int dx[]={1,0,-1,0,-1,1,-1,1}, dy[]={0,-1,0,1,-1,1,1,-1};

bool valid(int i,int j)
{
	return(i>=0&&i<y&&j>=0&&j<x);
}

int bfs(int m,int n)
{
	if(ti[m][n]==0)
      return 0;
    queue< pair<int,int> > Q;
	pair<int,int> a,b;
	a.first=m;
	a.second=n;
	Q.push(a);
	while(!Q.empty())
	{
		a=Q.front();
		Q.pop();
		for(int i=0;i<8;i++)
		{
			b.first=a.first+dx[i];
			b.second=a.second+dy[i];
			if(valid(b.first, b.second) && ti[b.first][b.second])
			{
				ti[b.first][b.second]=0;
				Q.push(b);
			}
		}
	}
	return 1;
}

int main()
{
	while(cin >> x >> y)
	{
		if(!x&&!y)
		  break;
		for(int i=0;i<y;i++)
		   for(int j=0;j<x;j++)
		   {
		   	    cin >> ti[i][j];
		   }
        int sum=0;
        for(int i=0;i<y;i++)
		   for(int j=0;j<x;j++)
              if(bfs(i,j))
              {
                  sum++;
              }
        cout << sum << endl;
	}
}

C++: #define _USE_MATH_DEFINES
#define INF 100000000

#include <iostream>
#include <sstream>
#include <cmath>
#include <cstdlib>
#include <algorithm>
#include <queue>
#include <stack>
#include <limits>
#include <map>
#include <string>
#include <cstring>
#include <set>
#include <deque>
#include <bitset>
#include <list>
#include <cctype>
#include <utility>

using namespace std;

typedef long long ll;
typedef pair <int,int> P;
typedef pair <int,P> PP;

static const double EPS = 1e-8;

int stage[50][50];

void dfs(int x,int y,int w,int h){
	stage[y][x] = 0;
	for(int tx=-1;tx<=1;tx++){
		for(int ty=-1;ty<=1;ty++){
			int dx = x + tx;
			int dy = y + ty;
			if(dx < 0 || dx >=w || dy < 0 || dy >= h) continue;

			if(stage[dy][dx]==1){
				dfs(x+tx,y+ty,w,h);
			}
		}
	}
}

int main(){
	int w,h;
	while(~scanf("%d %d",&w,&h)){
		if(w==h && h==0) break;
		for(int y=0;y<h;y++){
			for(int x=0;x<w;x++){
				scanf("%d",(*(stage+y)+x));
			}
		}

		int res=0;
		for(int y=0;y<h;y++){
			for(int x=0;x<w;x++){
				if(stage[y][x]==1){
					dfs(x,y,w,h);
					res++;
				}
			}
		}

		printf("%d\n",res);
	}
}