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++: // 1:23:44 (editorial)
#define DEBUG 1
#include <algorithm>
#include <cmath>
#include <cstring>
#include <deque>
#include <iomanip>
#include <iostream>
#include <map>
#include <queue>
#include <set>
#include <string>
#include <tuple>
#include <utility>
#include <vector>
using namespace std;
using ll = long long;
using vll = vector<ll>;
using vvll = vector<vll>;
using pll = pair<ll, ll>;
using tll = tuple<ll, ll, ll>;
#define all(v) (v).begin(), (v).end()
#define for1(i, n) for (ll i = 0; i < (n); i++)
#define for2(i, m, n) for (ll i = (m); i < (n); i++)
#define for3(i, m, n, d) for (ll i = (m); i < (n); i += (d))
#define rfor1(i, n) for (ll i = 0; i > (n); i--)
#define rfor2(i, m, n) for (ll i = (m); i > (n); i--)
#define rfor3(i, m, n, d) for (ll i = (m); i > (n); i += (d))
#define INF (1LL << 60)
#if DEBUG
#define dump(v1) dump_1(#v1, v1)
#define dump2(v1, v2) dump_2(#v1, v1, #v2, v2)
#define dump3(v1, v2, v3) dump_3(#v1, v1, #v2, v2, #v3, v3)
#define dump4(v1, v2, v3, v4) dump_4(#v1, v1, #v2, v2, #v3, v3, #v4, v4)
#else
#define dump(v1)
#define dump2(v1, v2)
#define dump3(v1, v2, v3)
#define dump4(v1, v2, v3, v4)
#endif
#if DEBUG
template <typename T>
void dump_1(const string& n1, const T& v1)
{
    cerr << n1 << ": " << v1 << endl;
}
template <typename T1, typename T2>
void dump_2(const string& n1, const T1& v1, const string& n2, const T2& v2)
{
    cerr << n1 << ": " << v1 << "  " << n2 << ": " << v2 << endl;
}
template <typename T1, typename T2, typename T3>
void dump_3(const string& n1, const T1& v1, const string& n2, const T2& v2,
            const string& n3, const T3& v3)
{
    cerr << n1 << ": " << v1 << "  " << n2 << ": " << v2 << "  " << n3 << ": "
         << v3 << endl;
}
template <typename T1, typename T2, typename T3, typename T4>
void dump_4(const string& n1, const T1& v1, const string& n2, const T2& v2,
            const string& n3, const T3& v3, const string& n4, const T4& v4)
{
    cerr << n1 << ": " << v1 << "  " << n2 << ": " << v2 << "  " << n3 << ": "
         << v3 << "  " << n4 << ": " << v4 << endl;
}
template <typename T1, typename T2>
ostream& operator<<(ostream& os, const pair<T1, T2>& v)
{
    os << "(" << v.first << ", " << v.second << ")";
    return os;
}
template <typename T1, typename T2, typename T3>
ostream& operator<<(ostream& os, const tuple<T1, T2, T3>& v)
{
    os << "(" << get<0>(v) << ", " << get<1>(v) << ", " << get<2>(v) << ")";
    return os;
}
template <typename T>
ostream& operator<<(ostream& os, const vector<T>& v)
{
    for (auto it = v.begin(); it != v.end(); it++) {
        if (it != v.begin()) {
            os << " ";
        }
        os << *it;
    }
    return os;
}
template <typename T>
ostream& operator<<(ostream& os, const set<T>& v)
{
    for (auto it = v.begin(); it != v.end(); it++) {
        if (it != v.begin()) {
            os << " ";
        }
        os << *it;
    }
    return os;
}
template <typename T1, typename T2>
ostream& operator<<(ostream& os, const map<T1, T2>& v)
{
    os << "{";
    for (auto it = v.begin(); it != v.end(); it++) {
        if (it != v.begin()) {
            os << ", ";
        }
        os << it->first << ":" << it->second;
    }
    os << "}";
    return os;
}
#endif  // DEBUG
void Yes(void) { cout << "Yes" << endl; }
void No(void) { cout << "No" << endl; }
void YES(void) { cout << "YES" << endl; }
void NO(void) { cout << "NO" << endl; }
template <typename T>
void inv(vector<T>& v, ll len)
{
    for1 (i, len) {
        cin >> v[i];
    }
}
template <typename T>
void print(const T& v)
{
    cout << v << endl;
}
//---------------------------------------------------------
void dfs(ll h, ll w, ll H, ll W, vvll& C)
{
    if (C[h][w] == 0) {
        return;
    }
    C[h][w] = 0;
    for2 (h2, h - 1, h + 2) {
        for2 (w2, w - 1, w + 2) {
            if (h2 == h && w2 == w) continue;
            if (0 <= h2 && h2 < H && 0 <= w2 && w2 < W) {
                dfs(h2, w2, H, W, C);
            }
        }
    }
}
void solve()
{
    ll ans = 0;
    ll W, H;
    while (true) {
        cin >> W >> H;
        if (W == 0 && H == 0) {
            return;
        }
        vvll C(H, vll(W));
        for1 (h, H) {
            for1 (w, W) {
                cin >> C[h][w];
            }
        }
        ans = 0;
        for1 (h, H) {
            for1 (w, W) {
                if (C[h][w] == 1) {
                    dfs(h, w, H, W, C);
                    ans++;
                }
            }
        }
        print(ans);
    }
}

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    solve();
}

C++: #include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for(int i=0; i<(n); ++i)
#define REP(i, d, n) for(int i=(d); i<(n); ++i)
#define all(v) v.begin(), v.end()

const int x[] = {-1, -1, -1, 0, 0, 1, 1, 1};
const int y[] = {-1, 0, 1, -1, 1, -1, 0, 1};

int dfs(int i, int j, vector<vector<int> >& graph, vector<vector<int> >& visit, const int h, const int w){
    if(visit[i][j] == 1 || graph[i][j] == 0){
        return 0;
    }
    visit[i][j] = 1;
    rep(k, 8){
        int di = i + x[k];
        int dj = j + y[k];
        if(di < 0 || dj < 0 || di >= h || dj >= w){
            continue;
        }
        if(visit[di][dj] == 1){
            continue;
        }
        dfs(di, dj, graph, visit, h, w);
    }
    return 1;
}

int main() {

    while(true){
        int w, h;
        cin >> w >> h;
        if(w == 0 && h == 0){
            break;
        }
        vector<vector<int> > graph(h, vector<int>(w)); 
        rep(i, h){
            rep(j, w){
                cin >> graph[i][j];
            }
        }
        vector<vector<int> > visit(h, vector<int>(w));
        int ans = 0;
        rep(i, h){
            rep(j, w){
                ans += dfs(i, j, graph, visit, h, w);
            }
        }
        cout << ans << endl;
    }

    return 0;
}

C++: #include<iostream>
#include<queue>
#include<cstring>
using namespace std;
int x[50][50], col[50][50], h, w, c, i, j, k, l, p, q;
queue<int>Q, R;
int main() {
	while (true) {
		c = 0;
		memset(col, 0, sizeof(col));
		cin >> w >> h;
		if (h == 0) { break; }
		for (i = 0; i < h; i++) { for (j = 0; j < w; j++) { cin >> x[i][j]; } }
		for (i = 0; i < 50; i++) {
			for (j = 0; j < 50; j++) {
				if (x[i][j] == 1 && col[i][j] == 0) {
					c++;
					col[i][j] = c;
					Q.push(i * 100 + j);
					while (!Q.empty()) {
						while (!Q.empty()) {
							p = Q.front() / 100;
							q = Q.front() % 100;
							for (k = -1; k < 2; k++) {
								for (l = -1; l < 2; l++) {
									if (x[p + k][q + l] == 1 && col[p + k][q + l] == 0) {
										col[p + k][q + l] = c;
										R.push((p + k) * 100 + q + l);
									}
								}
							}
							Q.pop();
						}
						while (!R.empty()) {
							Q.push(R.front());
							R.pop();
						}
					}
				}
			}
		}
		cout << c << endl;
	}
}