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>

#define rep(i, n) for (int i = 0; i < int(n); i++)
#define rrep(i, n) for (int i = int(n) - 1; i >= 0; i--)
#define reps(i, n) for (int i = 1; i <= int(n); i++)
#define rreps(i, n) for (int i = int(n); i >= 1; i--)
#define repc(i, n) for (int i = 0; i <= int(n); i++)
#define rrepc(i, n) for (int i = int(n); i >= 0; i--)
#define repi(i, a, b) for (int i = int(a); i < int(b); i++)
#define repic(i, a, b) for (int i = int(a); i <= int(b); i++)
#define each(x, y) for (auto &x : y)
#define all(a) (a).begin(), (a).end()
#define bit(b) (1ll << (b))

using namespace std;

using i32 = int;
using i64 = long long;
using u64 = unsigned long long;
using f80 = long double;
using vi32 = vector<i32>;
using vi64 = vector<i64>;
using vu64 = vector<u64>;
using vf80 = vector<f80>;
using vstr = vector<string>;

inline void yes() { cout << "Yes" << '\n'; exit(0); }
inline void no() { cout << "No" << '\n'; exit(0); }
inline i64 gcd(i64 a, i64 b) { if (min(a, b) == 0) return max(a, b); if (a % b == 0) return b; return gcd(b, a % b); }
inline i64 lcm(i64 a, i64 b) { return a / gcd(a, b) * b; }
inline u64 xorshift() { static u64 x = 88172645463325252ull; x = x ^ (x << 7); return x = x ^ (x >> 9); }
void solve(); int main() { ios::sync_with_stdio(0); cin.tie(0); cout << fixed << setprecision(16); solve(); return 0; }
template <typename T> class pqasc : public priority_queue<T, vector<T>, greater<T>> {};
template <typename T> class pqdesc : public priority_queue<T, vector<T>, less<T>> {};
template <typename T> inline void amax(T &x, T y) { if (x < y) x = y; }
template <typename T> inline void amin(T &x, T y) { if (x > y) x = y; }
template <typename T> inline T power(T x, i64 n, T e = 1) { T r = e; while (n > 0) { if (n & 1) r *= x; x *= x; n >>= 1; } return r; }
template <typename T> istream& operator>>(istream &is, vector<T> &v) { each(x, v) is >> x; return is; }
template <typename T> ostream& operator<<(ostream &os, vector<T> &v) { rep(i, v.size()) { if (i) os << ' '; os << v[i]; } return os; }
template <typename T, typename S> istream& operator>>(istream &is, pair<T, S> &p) { is >> p.first >> p.second; return is; }
template <typename T, typename S> ostream& operator<<(ostream &os, pair<T, S> &p) { os << p.first << ' ' << p.second; return os; }

void solve() {
  while (true) {
    int w, h; cin >> w >> h;
    if (w == 0) return;
    vector<vi32> a(h, vi32(w));
    rep(i, h) cin >> a[i];
    function<void(int, int)> dfs = [&](int x, int y) {
      a[x][y] = 0;
      for (int i = -1; i <= 1; i++)
      for (int j = -1; j <= 1; j++) {
        if (i == 0 && j == 0) continue;
        int wx = x + i, wy = y + j;
        if (wx < 0 || wx >= h || wy < 0 || wy >= w) continue;
        if (a[wx][wy] == 0) continue;
        dfs(wx, wy);
      }
    };
    int ans = 0;
    rep(i, h) rep(j, w) if (a[i][j] == 1) ans++, dfs(i, j);
    cout << ans << '\n';
  }
}

C++: #include <iostream>
using namespace std;
void dfs(int,int);
int data[52][52];
int main(){
  int w,h,i,j,cnt;
  while(1){
    cnt=0;
    cin >> w >> h;
    if(w==0&&h==0) break;
    for(i=0;i<=h+1;i++){
      for(j=0;j<=w+1;j++){
    data[i][j]=0;
      }
    }
    for(i=1;i<=h;i++){
      for(j=1;j<=w;j++){
    cin >> data[i][j];
      }
    }
    for(i=1;i<=h;i++){
      for(j=1;j<=w;j++){
        if(data[i][j]==1){
      dfs(i,j);
      cnt++;
    }
      }
    }
    cout << cnt << endl;
  }
  return 0;
}
void dfs(int i,int j){
  if(data[i][j]==0) return ;
  data[i][j]=0;
  dfs(i-1,j);
  dfs(i+1,j);
  dfs(i,j-1);
  dfs(i,j+1);
  dfs(i-1,j-1);
  dfs(i-1,j+1);
  dfs(i+1,j-1);
  dfs(i+1,j+1);
}

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

#define PIAR pair<int, int>

struct pos{
    int x;
    int y;
};

int main(){
    int w, h;
    while(cin >> w >> h, w != 0 && h != 0){
        int field[52][52] = {{0}};
        for(int i = 1; i <= h; i++){
            for(int j = 1; j <= w; j++){
                cin >> field[i][j];
            }
        }

        stack<PIAR> st;
        int island = 0;
        int dx[] = {-1,  0, 1, 0, -1,  1, 1, -1};
        int dy[] = {0 , -1, 0, 1, -1, -1, 1,  1};
        for(int i = 1; i <= h; i++){
            for(int j = 1; j <= w; j++){
                //島を探す
                if(field[i][j] == 1){
                    st.push(PIAR(j, i));
                    field[i][j] = 0;
                    while(!st.empty()){
                    	int x = st.top().first;
                    	int y = st.top().second;
                        st.pop();
                        for(int k = 0; k < 8; k++){
                            int nextX = x + dx[k];
                            int nextY = y + dy[k];
                            if(field[nextX][nextY] == 1){
                                st.push(PIAR(nextX, nextY));
                                field[nextX][nextY] = 0;
                            }
                        }
                    }
                    island++;
                }

            }
        }

        cout << island << endl;
    }
}

C++: #include<bits/stdc++.h>
#define rep(i,N) for(int i=0;i<(N);i++)
#define FOR(i,a,b) for(int i=(a);i<(b);i++)
using namespace std;
const long long MOD = 1e9 + 7;
const long long INF = 1e12;
const int inf = 1e9;
typedef long long ll;
typedef pair<int,int> P;
typedef set<int> S;
ll n;
int maze[55][55];
int attac[55][55];
int dx[] = {1,-1,0,0,1,-1,1,-1};
int dy[] = {0,0,1,-1,1,1,-1,-1};
int w,h;
void bfs(int i,int j){
    queue<P> que;
    que.push({i,j});
    //cout<<"111"<<endl;
    while(!que.empty()){
        P now;
        now = que.front();
        que.pop();
        int x = now.first;
        int y = now.second;
        rep(k,8){
            //cout<<"aaa"<<endl;
            int nx = x + dx[k];
            int ny = y + dy[k];
            if(nx<h && nx>=0 && ny<w && ny>=0 && attac[nx][ny]==0 && maze[nx][ny]==1){
                //cout<<"ああ"<<endl;
                attac[nx][ny]=1;
                que.push({nx,ny});
            }
        }
    }
}
int main(){
    while (1){
        int ans=0;
        cin>>w>>h;
        if(w==0 && h==0) break;
        rep(i,55){
            rep(j,55) attac[i][j]=0;
        }
        rep(i,h){
            rep(j,w) cin>>maze[i][j];
        }
        rep(i,h){
            rep(j,w){
                if(maze[i][j]==1 && attac[i][j]==0){
                    ans++;
                    bfs(i,j);
                }
            }
        }
        cout<<ans<<endl;
    }
    
    return 0;
}