Go: // AOJ 1160: How Many Islands? http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=1160

package main

import (
	"bufio"
	"container/list"
	"fmt"
	"os"
	"strconv"
)

var SEA = 0
var LAND = 1

func nextInt(sc *bufio.Scanner) int {
	sc.Scan()
	v, _ := strconv.Atoi(sc.Text())
	return v
}

func discoverIslands(M, V [][]int, H, W int) int {
	// 島を探す
	queue := list.New()
	islands := 0
	for i := 1; i <= H; i++ {
		for j := 1; j <= W; j++ {
			// 訪問済みの土地ならスキップ
			if V[i][j] == 1 {
				continue
			}

			// 訪問中の土地が海なら訪問済みにしてスキップ
			if M[i][j] == SEA {
				V[i][j] = 1
				continue
			}

			// 未訪問の陸地が見つかったので
			// 島の数を1つ増やし、この陸地から辿れる陸地を訪問していく
			islands++
			queue.PushBack([]int{i, j})

			for queue.Len() > 0 {
				cur := queue.Remove(queue.Front()).([]int)
				h, w := cur[0], cur[1]
				if V[h][w] == 1 {
					continue
				}
				V[h][w] = 1

				// 全方向に未訪問の陸地がないか探索
				for v := -1; v <= 1; v++ {
					for l := -1; l <= 1; l++ {
						dh := h + v
						dw := w + l
						if M[dh][dw] == LAND && V[dh][dw] == 0 {
							queue.PushBack([]int{dh, dw})
						}
					}
				}
				/*
					if M[h-1][w] == LAND {
						queue.PushBack([]int{h - 1, w})
					}
					if M[h-1][w+1] == LAND {
						queue.PushBack([]int{h - 1, w + 1})
					}
					if M[h][w+1] == LAND {
						queue.PushBack([]int{h, w + 1})
					}
					if M[h+1][w+1] == LAND {
						queue.PushBack([]int{h + 1, w + 1})
					}
					if M[h+1][w] == LAND {
						queue.PushBack([]int{h + 1, w})
					}
					if M[h+1][w-1] == LAND {
						queue.PushBack([]int{h + 1, w - 1})
					}
					if M[h][w-1] == LAND {
						queue.PushBack([]int{h, w - 1})
					}
					if M[h-1][w-1] == LAND {
						queue.PushBack([]int{h - 1, w - 1})
					}
				*/
			}
		}
	}
	return islands
}

func main() {
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)

	for {
		W, H := nextInt(sc), nextInt(sc)

		if W == 0 && H == 0 {
			break
		}
		// Initialize map and visted list
		M := make([][]int, H+2)
		V := make([][]int, H+2)
		for i := 0; i < H+2; i++ {
			M[i] = make([]int, W+2)
			V[i] = make([]int, W+2)
		}
		for i := 1; i <= H; i++ {
			for j := 1; j <= W; j++ {
				M[i][j] = nextInt(sc)
			}
		}

		islands := discoverIslands(M, V, H, W)

		fmt.Println(islands)
	}
}

C++: #include <iostream>
#include <vector>

using namespace std;

static int W, H;
static vector<vector<int>> field;

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

void dfs(int x, int y) {
    if (x < 0 || x >= W || y < 0 || y >= H || field[y][x] == 0)
        return;

    field[y][x] = 0;
    for (int k = 0; k < 8; k++)
        dfs(x + dx[k], y + dy[k]);
}

int main() {
    for (;;) {
        cin >> W >> H;
        if (W == 0) break;

        field.resize(H);
        for (int y = 0; y < H; y++) {
            field[y].resize(W);
            for (int x = 0; x < W; x++) {
                cin >> field[y][x];
            }
        }

        int ans = 0;
        for (int y = 0; y < H; y++) {
            for (int x = 0; x < W; x++) {
                if (field[y][x] == 1) {
                    dfs(x, y);
                    ans++;
                }
            }
        }

        cout << ans << endl;
    }
}

C++: #include<iostream>
using namespace std;
int dx[]={0,1,0,-1,1,1,-1,-1},dy[]={1,0,-1,0,1,-1,1,-1};
struct E{
	int w,h;
	int ma[50][50],color[50][50];
	bool used[50][50];
	int col;
	int init(int _w,int _h)
	{
		w=_w,h=_h;
		for(int i=0;i<h;i++)
		{
			for(int j=0;j<w;j++)
			{
				cin>>ma[i][j];
				used[i][j]=color[i][j]=0;
			}
		}
	}
	void dfs(int x,int y)
	{
		used[x][y]=1;
		color[x][y]=col;
		for(int r=0;r<8;r++)
		{
			int tx=x+dx[r],ty=y+dy[r];
			if(tx<0||ty<0||tx>=h||ty>=w||ma[tx][ty]==0||used[tx][ty])continue;
			dfs(tx,ty);
		}
	}
	void solve()
	{
		col=0;
		for(int i=0;i<h;i++)
		{
			for(int j=0;j<w;j++)
			{
				if(used[i][j]||ma[i][j]==0)continue;
				col++;
				dfs(i,j);
			}
		}
		cout<<col<<endl;
	}
};
main()
{
	int a,b;
	while(cin>>a>>b,a)
	{
		E s;s.init(a,b);s.solve();
	}
}

C++: #include <cstdio>
#include <cstring>
#include <cmath>
#include <iostream>
#include <sstream>
#include <algorithm>
#include <numeric>
#include <functional>
#include <vector>
#include <queue>
#include <string>
#include <complex>

#define REP(i,n) for (int i = 0; i < (n); i++)
#define FOR(i,s,n) for (int i = (s); i < (n); i++)
#define ALLOF(c) c.begin(), c.end()
#define RANGEOF(c,i,n) c.begin() + (i), c.begin() + (i) + (n)
#define EPS 1e-9
#define INF 1000000000
using namespace std;

typedef complex<int> POINT;
template <class T>
class vevector : public vector<vector<T>>
{
public:
	using vector<vector<T>>::operator []; 
	T& operator [](const POINT &index) { return (*this)[index.real()][index.imag()]; }
};

template <class T> T read() { T t; cin >> t; return t; }
template <class T> vector<T> read(int n) { vector<T> v; REP(i,n) { v.push_back(read<T>()); } return v; }
template <class T> vevector<T> read(int n, int m) { vevector<T> v; REP(i,n) v.push_back(read<T>(m)); return v; }
template <class T> void write(const T &t) { cout << t << endl; }
template <class T> void write(const T &t, const T &t2) { cout << t << ' ' << t2 << endl; }

template <class T> void write(const vector<T> &v)
{
	ostringstream ss; 
	for (auto x : v) ss << x << ' ';
	auto s = ss.str();
	cout << s.substr(0, s.length() - 1) << endl;
}

struct _Reader { template <class T> _Reader operator ,(T &rhs) { cin >> rhs; return *this; } };
#define READ(t,...) t __VA_ARGS__; _Reader(), __VA_ARGS__

void solve();
int main() { solve(); return 0; }


/// template end ///



void solve()
{
	while (true)
	{
		READ(int, H, W);
		if (!(W|H)) { break; }
		auto field = read<char>(W, H);
		for (auto &f : field) { f.insert(f.begin(), '0'); f.push_back('0'); }
		field.insert(field.begin(), vector<char>(H+2, '0'));
		field.push_back(vector<char>(H+2, '0'));
		W += 2; H += 2;

		int count = 0;
		REP(sx,W) REP(sy,H) if (field[sx][sy] == '1')
		{
			typedef POINT P;
			queue<P> q;
			q.push(P(sx, sy));
			while (!q.empty())
			{
				P cur = q.front(); q.pop();
				if (field[cur] == '0') { continue; }
				field[cur] = '0';
				P d[] = { P(-1,-1), P(0,-1), P(1,-1), P(-1, 0), P(1, 0), P(-1,1), P(0,1), P(1,1) };
				REP(i, 8)
				{
					P next = cur + d[i];
					if (field[next] == '1') q.push(next);
				}
			}
			count++;
		}
		write(count);
	}
}

C++: #include<iostream>
#define N 51
using namespace std;

int w, h, ans = 0, map[N][N];

void search_zahyou(int w, int h);

int main(){
	while(cin >>w >>h){
		ans = 0;
		if(w == 0 && h == 0) break;
		for(int i = 0; i < h; i++){
			for(int k = 0; k < w; k++){
				cin >>map[i][k];
			}
		}
		for(int i = 0; i < h; i++){
			for(int k = 0; k < w; k++){
				if(map[i][k] == 0){
					continue;
				}
				else{
					ans++;
					search_zahyou(i, k);
				}
			}
		}
		cout <<ans <<endl;
	}
	return 0;
}

void search_zahyou(int inh, int inw){
	char searchh[8] = {-1, -1, -1, 0, 1, 1, 1, 0}, searchw[8] = {-1, 0, 1, 1, 1, 0, -1, -1};
	if(h <= inh || w <= inw){
	} else{
		map[inh][inw] = 0;
		for(int i = 0; i < 8; i++){
			if(map[inh + searchh[i]][inw + searchw[i]] == 1){
				search_zahyou(inh + searchh[i], inw + searchw[i]);
			}
		}
	}
}