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 <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef pair<ll, ll> P;
typedef pair<int, int> Pi;
typedef vector<ll> Vec;
typedef vector<int> Vi;
typedef vector<string> Vs;
typedef vector<P> VP;
typedef vector<vector<ll>> VV;
typedef vector<vector<int>> VVi;

#define REP(i, a, b) for(ll i=(a); i<(b); i++)
#define PER(i, a, b) for(ll i=(a); i>=(b); i--)
#define rep(i, n) REP(i, 0, n)
#define per(i, n) PER(i, n, 0)
const ll INF=1e18+18;
const ll MAX=100005;
const ll MOD=1000000007;
#define Yes(n) cout << ((n) ? "Yes" : "No") << endl;
#define YES(n) cout << ((n) ? "YES" : "NO") << endl;
#define ALL(v) v.begin(), v.end()
#define rALL(v) v.rbegin(), v.rend()
#define pb(x) push_back(x)
#define mp(a, b) make_pair(a,b)
#define Each(a,b) for(auto &a :b)
#define REPM(i, mp) for (auto i = mp.begin(); i != mp.end(); ++i)
#define dbg(x_) cerr << #x_ << ":" << x_ << endl;
#define dbgmap(mp) cerr << #mp << ":"<<endl; for (auto i = mp.begin(); i != mp.end(); ++i) { cerr << i->first <<":"<<i->second << endl;}
#define dbgarr(n,m,arr) rep(i,n){rep(j,m){cerr<<arr[i][j]<<" ";}cerr<<endl;}
#define dbgdp(n,arr) rep(i,n){cerr<<arr[i]<<" ";}cerr<<endl;
#define dbgmint(n,arr) rep(i,n){cerr<<arr[i].x<<" ";}cerr<<endl;
#define out(a) cout<<a<<endl
#define out2(a,b) cout<<a<<" "<<b<<endl
#define vout(v) rep(i,v.size()){cout<<v[i]<<" ";}cout<<endl
#define Uniq(v) v.erase(unique(v.begin(), v.end()), v.end())
#define fi first
#define se second

template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return true; } return false; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return true; } return false; }

template<typename T1, typename T2>
ostream &operator<<(ostream &s, const pair<T1, T2> &p) { return s<<"("<<p.first<<", "<<p.second<<")"; }

template<typename T>istream& operator>>(istream&i,vector<T>&v)
{rep(j,v.size())i>>v[j];return i;}

// vector
template<typename T>
ostream &operator<<(ostream &s, const vector<T> &v) {
    int len=v.size();
    for(int i=0; i<len; ++i) {
        s<<v[i];
        if(i<len-1) s<<"	";
    }
    return s;
}

// 2 dimentional vector
template<typename T>
ostream &operator<<(ostream &s, const vector<vector<T> > &vv) {
    int len=vv.size();
    for(int i=0; i<len; ++i) {
        s<<vv[i]<<endl;
    }
    return s;
}

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    cout<<std::setprecision(10);

    while(true){
        ll ans=0;
        ll w,h;
        cin>>w>>h;
        if(w==0&&h==0)break;
        VV g(h+2,Vec(w+2));
        VV d(h+2,Vec(w+2,-1));
        rep(i,h){
            rep(j,w){
                cin>>g[i+1][j+1];
            }
        }
        Vec dx = {1,0,-1,0,1,1,-1,-1};
        Vec dy = {0,1,0,-1,1,-1,1,-1};
        rep(i,h){
            rep(j,w){
                if(g[i+1][j+1]==0)continue;
                if(d[i+1][j+1]==-1){
                    VV visited(h+2,Vec(w+2));
                    auto dfs = [&](auto dfs,ll y,ll x)->void{
                        visited[y][x] = 1;
                        rep(i,8){
                            ll nx = x + dx[i];
                            ll ny = y + dy[i];
                            if(g[ny][nx]==1 && visited[ny][nx]==0){
                                d[ny][nx] = d[y][x]+1;
                                dfs(dfs,ny,nx);
                            }
                        }
                        //visited[y][x] = 0;
                    };
                    ans++;
                    d[i+1][j+1] = 1;
                    dfs(dfs,i+1,j+1);
                }
            }
        }
        cout<<ans<<endl;
    }
    return  0;
}

C++: #include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const ll INF = 1e18;
const int inf = 1e9;
#define rep(i, a, b) for (int i = a; i < b; i++)
#define per(i, b, a) for (int i = a - 1; i >= b; i--)
using Graph = vector<vector<int>>;
using pint = pair<int, int>;
int dx[4] = {1, 0, -1, 0}, dy[4] = {0, 1, 0, -1};
int dxx[8] = {1, 1, 1, 0, 0, -1, -1, -1}, dyy[8] = {-1, 0, 1, -1, 1, -1, 0, 1};

bool seen[55][55];
int ans = 0;
int c[55][55];

bool dfs (int y, int x, int w, int h) {
    if (seen[y][x] || c[y][x] == 0) return false;
    seen[y][x] = true;
    rep (i, 0, 8) {
        int ny = y + dyy[i], nx = x + dxx[i];
        if (ny >= 0 && ny < h && nx >= 0 && nx < w && !seen[ny][nx] &&
            c[ny][nx] == 1) {
            dfs (ny, nx, w, h);
        }
    }
    return true;
}

int main() {
    int w, h;
    while (1) {
        cin >> w >> h;
        if (w == 0 && h == 0) break;
        rep (i, 0, h) rep (j, 0, w) cin >> c[i][j];
        rep (i, 0, h) rep (j, 0, w) seen[i][j] = 0;
        int ans = 0;
        rep (i, 0, h) {
            rep (j, 0, w) {
                if (dfs (i, j, w, h)) {
                    // cout << i << " " << j << "\n";
                    ans++;
                }
            }
        }
        cout << ans << "\n";
    }
}

C++: #include<iostream>
using namespace std;
int dx[]={1,0,-1,0,1,-1,-1,1};
int dy[]={0,1,0,-1,1,-1,1,-1};
int field[150][150];
void dfs(int x, int y);
int main(){
  int h,w;
  while(cin >>h>>w,h||w){
    for(int i=0; i<150; i++) for(int j=0; j<150; j++) field[i][j] = 0;
    for(int i=0; i<w; i++) for(int j=0; j<h; j++) cin >>field[i+50][j+50];
    int ans = 0;
    for(int i=0; i<w; i++){
      for(int j=0; j<h; j++){
	if(field[i+50][j+50] == 1){
	  dfs(i+50,j+50);
	  ans++;
	}
      }
    }
    cout <<ans<<endl;
  }
  return 0;
}
void dfs(int x, int y){
  field[x][y] = 0;
  for(int i=0; i<8; i++) if(field[x+dx[i]][y+dy[i]] == 1) dfs(x+dx[i],y+dy[i]);
}

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

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

int main() {
	int w, h, ans, x, y;
	int c[52][52], f[52][52];
	queue< pair<int, int> > q;
	while(1) {
		cin >> w >> h;
		if(!w&&!h) break;
		for(int i=0; i<h+2; ++i) for(int j=0; j<w+2; ++j) {
			c[i][j] = 0; f[i][j] = 0;
		}
		ans = 0;
		
		for(int i=1; i<=h; ++i) for(int j=1; j<=w; ++j) {
			cin >> c[i][j];
		}
		for(int i=1; i<=h; ++i) for(int j=1; j<=w; ++j) {
			if(c[i][j]&&!f[i][j]) {
				ans++;
				q.push( pair<int, int>(i, j) );
				while(!q.empty()) {
					y = q.front().first; x = q.front().second;
					q.pop();
					f[y][x] = 1;
					for(int k=0; k<8; ++k) {
						if(c[y+dy[k]][x+dx[k]]&&!f[y+dy[k]][x+dx[k]]) {
							q.push( pair<int, int>(y+dy[k], x+dx[k]) );
						}
					}
				}
			}
		}
		cout << ans << endl;
	}
}