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 <iostream>
#include <string>
#include <algorithm>
#include <vector>
#include <cmath>
#include <cstdlib>
#include <tuple>
using namespace std;
using ll=long long;
using R=double;

int w,h;

int dx[8] = {0, 1, 1, 1, 0, -1, -1, -1};
int dy[8] = {1, 1, 0, -1, -1, -1, 0, 1};
int field[50][50];

void dfs(int w, int h){
	field[h][w] = 0;

	for(int nh=h-1;nh<h+2;nh++){
	    for(int nw=w-1;nw<w+2;nw++){
	      if(field[nh][nw]==1&&0<=nh&&0<=nw&&nh<h&&nw<w)dfs(nw,nh);
	    }
	  }
	return;
}

int main(){
	while(1){
		cin >> w >> h;
		if(w==0 and h==0){
			break;
		}

		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]==1){
					count++;
					dfs(j,i);
				}
			}
		}
		cout << count << endl;
	}
	return 0;
}

C++: #include <iostream>
using namespace std;
int w,h;
int in[100][100];
bool seen[100][100];
int ans =0;
bool flag = false;

void solve(int i,int j){
    //cout << i << " " << j << endl;
    if(i < 0 || j < 0 || i >= h || j >= w){
        return;
    }
    if(seen[i][j]){
        return;
    }
    if(in[i][j] == 0){
        return;
    }
    seen[i][j] = true;
    solve(i-1,j-1);
    solve(i-1,j);
    solve(i-1,j+1);
    solve(i,j-1);
    solve(i,j+1);
    solve(i+1,j-1);
    solve(i+1,j);
    solve(i+1,j+1);

}
int main(){
    cin >> w >> h;
    for(int i=0;i<h;i++){
        for(int j=0;j<w;j++){
            cin >> in[i][j];
        }
    }
    for(int i=0;i<h;i++){
        for(int j=0;j<w;j++){
            if(seen[i][j] == true || in[i][j] == 0){
            }
            else{
                solve(i,j);
                ans++;
            }
            
        }
    }
    cout << ans << endl;
    return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
#define int long long
#define rep(i, n) for(int i = 0; i < n; i++)
#define all(a) a.begin(), a.end()
#define P pair<int, int>
#define F first
#define S second
#define prime 1000000007
#define INF 40000000000000000
int dx8[8] = {-1, 0, 1, 1, 1, 0, -1, -1};
int dy8[8] = {1, 1, 1, 0, -1, -1, -1, 0};
int dx4[4] = {-1, 0, 1, 0};
int dy4[4] = {0, -1, 0, 1};
bool Grid[51][51];
int w, h;
void dfs(int x, int y) {
    //cout << x << ':' << y << "HaHaHaHa" << endl;
    rep(i, 8) {
        int nx = x + dx8[i];
        int ny = y + dy8[i];
        //cout << x << ':' << dx8[i] << ' ' << y << ':' << dy8[i] << ' ' << nx << ':' << ny << endl;
        if(nx < 0 || nx >= h || ny < 0 || ny >= w) continue;
        if(Grid[nx][ny]) {
            Grid[nx][ny] = false;
            dfs(nx, ny);
        }
    }
}
signed main(void) {
    while(true) {
        cin >> w >> h;
        if(w == 0 && h == 0) return 0;
        rep(i, 51) rep(j, 51) Grid[i][j] = false;
        rep(i, h) rep(j, w) {
            int x;
            cin >> x;
            if(x == 1) Grid[i][j] = true;
        }
        int ans = 0;
        rep(i, h) rep(j, w) {
            if(Grid[i][j]) {
                ans++;
                Grid[i][j] = false;
                dfs(i, j);
            }
        }
        cout << ans << endl;
    }
}

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

int f[64][64] = {0};
int dx[] = {0,0,1,1,1,-1,-1,-1};
int dy[] = {1,-1,0,1,-1,0,1,-1};

void dfs(int y, int x)
{
	f[y][x] = 0;
	for(int i=0; i<8; i++)
	{
		int ny = y+dy[i];
		int nx = x+dx[i];
		if(f[ny][nx])
		{
			dfs(ny,nx);
		}
	}
}

int main()
{
	int w,h,c,x,y;
	while(cin >> w >> h, w||h)
	{
		memset(f,0,sizeof(f));

		for(y=1; y<=h; y++)
		for(x=1; x<=w; x++)
		{
			cin >> f[y][x];
		}

		c=0;
		for(y=1; y<=h; y++)
		for(x=1; x<=w; x++)
		{
			if(f[y][x])
			{
				c++;
				dfs(y,x);
			}
		}
		cout << c << endl;
	}
}