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;

#define llong long long 
int w,h;
int sum;
int area[50][50];
int nw[8] = {0, 1, 1, 1, 0, -1, -1, -1};
int nh[8] = {1, 1, 0, -1, -1, -1, 0, 1};

void solve(int h, int w){
	if(area[h][w] == 0)return;
	area[h][w] == 0;
	for(int i = 0; i < 8; i++){
		int sh = h + nh[i];
		int sw = w + nw[i];
		if(sh < 0 || sw < 0 || sh >= h || sw >= w) continue;
		solve(sh, sw);
	}
	return;
}

int main(){

	while(cin >> w >> h, w){
		sum = 0;
		fill_n(*area, 50 * 50, 0);
		for(int i = 0; i < h; i++){
			for(int j = 0; j < w; j++){
				cin >> area[i][j];
			}
		}	

		for(int i = 0; i < h; i++){
			for(int j = 0; j < w; j++){
				if(area[i][j] == 1){
					sum++;
					solve(i, j);
				}
			}
		}

		cout << sum << endl;
	return 0;
}

C++: #include <bits/stdc++.h>

using namespace std;

#define REP(i, n) for (int i=0; i<(n); ++i)
#define RREP(i, n) for (int i=(int)(n)-1; i>=0; --i)
#define FOR(i, a, n) for (int i=(a); i<(n); ++i)
#define RFOR(i, a, n) for (int i=(int)(n)-1; i>=(a); --i)

#define SZ(x) ((int)(x).size())
#define all(x) begin(x),end(x)

#define dump(x) cerr<<#x<<" = "<<(x)<<endl
#define debug(x) cerr<<#x<<" = "<<(x)<<" (L"<<__LINE__<<")"<<endl;

template<class T>
ostream &operator<<(ostream &os, const vector <T> &v) {
    os << "[";
    REP(i, SZ(v)) {
        if (i) os << ", ";
        os << v[i];
    }
    return os << "]";
}

template<class T, class U>
ostream &operator<<(ostream &os, const pair <T, U> &p) {
    return os << "(" << p.first << " " << p.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;
}

using ll = long long;
using ull = unsigned long long;
using ld = long double;
using P = pair<int, int>;
using vi = vector<int>;
using vll = vector<ll>;
using vvi = vector<vi>;
using vvll = vector<vll>;

const ll MOD = 1e9 + 7;
const int INF = INT_MAX / 2;
const ll LINF = LLONG_MAX / 2;
const ld EPS = 1e-9;


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

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

    for (;;) {
        int w, h; cin >> w >> h;
        if (w == 0) break;

        vvi s(h, vi(w));
        REP(i, h) REP(j, w) cin >> s[i][j];

        vvi vis(h, vi(w));
        function<void(int,int)> dfs = [&](int i, int j) {
            vis[i][j] = 1;
            REP(k, 8) {
                int y = i + dy[k], x = j + dx[k];
                if (y < 0 or x < 0 or y >= h or x >= w) continue;
                if (s[y][x] == 0) continue;
                if (vis[y][x]) continue;
                dfs(y, x);
            }
        };

        int ans = 0;
        REP(i, h) REP(j, w) if (s[i][j] == 1 and !vis[i][j]) {
            ++ans;
            dfs(i, j);
        }
        cout << ans << endl;
    }

    return 0;
}

C++: #define _CRT_SECURE_NO_WARNINGS
#include"bits/stdc++.h"
#define INF          1e9
#define INFLL        1e18
#define EPS          1e-9
#define MOD          1000000007
#define REP(i,n)     for(ll i=0,i##_len=(n);i<i##_len;++i)
#define REP1(i,n)    for(ll i=1,i##_len=(n);i<=i##_len;++i)
#define REPR(i,n)    for(ll i=(n)-1;i>=0;--i)
#define REPR1(i,n)   for(ll i=(n);i>0;--i)
#define REPC(i,obj)  for(auto i:obj)
#define ALL(obj)     (obj).begin(),(obj).end()
#define SETP(n)      cout<<fixed<<setprecision(n)
#define VV(T,h,w)    vector<vector<T>>(h,vector<T>(w))
#define VVI(T,h,w,i) vector<vector<T>>(h,vector<T>(w,i))
using namespace std;
using ll = long long;
template<typename T = ll>inline T in() { T ret; cin >> ret; return ret; }

int main()
{
    while (true) {
        ll w = in(), h = in();
        if (w == 0 && h == 0)break;
        auto mp = VVI(ll, h + 2, w + 2, 0);
        REP(i, h) {
            REP(j, w) {
                mp[i + 1][j + 1] = in();
            }
        }
        ll ans = 0;
        REP(i, h) {
            REP(j, w) {
                if (mp[i + 1][j + 1] == 1) {
                    stack<pair<ll, ll>>st; st.emplace(i + 1, j + 1);
                    while (!st.empty()) {
                        auto cood = st.top(); st.pop();
                        mp[cood.first][cood.second] = 2;
                        for (ll dy = -1; dy <= 1; ++dy) {
                            for (ll dx = -1; dx <= 1; ++dx) {
                                ll y = cood.first + dy, x = cood.second + dx;
                                if (mp[y][x] == 1) {
                                    st.emplace(y, x);
                                }
                            }
                        }
                    }
                    ++ans;
                }
            }
        }
        cout << ans << endl;
    }
}

C++: #include <bits/stdc++.h>

using namespace std;

struct posi {
	int x;
	int y;
};

int main() {

	while (1) {
		int w, h;
		cin >> w >> h;

		if (w == 0 && h == 0) { return 0; }
		vector<vector<int>> mapp(h + 2, vector<int>(w + 2));
		for (int i = 1; i <= h; i++) {
			for (int j = 1; j <= w; j++) {
				cin >> mapp[i][j];
			}
		}


		vector<int> dx{ 1,1,0,-1,-1,-1,0,1 };
		vector<int> dy{ 0,1,1,1,0,-1,-1,-1 };

		vector<vector<bool>> seen(h + 2, vector<bool>(w + 2, false));
		deque<posi> todo; //考え方はスタックだけどdequeの方が使い勝手がいい


		posi s; //今いる場所
		int counter = 0;
		for (int i = 1; i <= h; i++) {
			for (int j = 1; j <= w; j++) {
				if (mapp[i][j] == 0) { continue; }
				//seen.resize(h + 2, vector<bool>(w + 2, false));

				if (seen[i][j] == false) {
					counter++;
					seen[i][j] = true;
					todo.push_back({ i,j });

					while (todo.empty() != true) {
						s = todo.back();
						bool tugiflg = false; //次があったらtrue
						for (int k = 0; k < 8; k++) {
							if (seen[s.x + dx[k]][s.y + dy[k]] != true) {
								seen[s.x + dx[k]][s.y + dy[k]] = true;
								if (mapp[s.x + dx[k]][s.y + dy[k]] == 1) {
									todo.push_back({ s.x + dx[k],s.y + dy[k] });;
									tugiflg = true;
									break;
								}
							}
						}
						if (tugiflg == false) {
							todo.pop_back();
						}
					}
				}
			}
		}

		cout << counter << endl;
	}
	return 0;

}