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> 
#include<queue>
using namespace std;

int x,y;
int ti[51][51];
const int dx[]={1,0,-1,0,-1,1,-1,1}, dy[]={0,-1,0,1,-1,1,1,-1};

bool valid(int i,int j)
{
	return(i>=0&&i<y&&j>=0&&j<x);
}

int bfs(int m,int n)
{
	if(ti[m][n]==0)
      return 0;
    queue< pair<int,int> > Q;
	pair<int,int> a,b;
	a.first=m;
	a.second=n;
	Q.push(a);
	while(!Q.empty())
	{
		a=Q.front();
		Q.pop();
		for(int i=0;i<8;i++)
		{
			b.first=a.first+dx[i];
			b.second=a.second+dy[i];
			if(valid(b.first, b.second) && ti[b.first][b.second])
			{
				ti[b.first][b.second]=0;
				Q.push(b);
			}
		}
	}
	return 1;
}

int main()
{
	while(cin >> x >> y)
	{
		if(!x&&!y)
		  break;
		for(int i=0;i<y;i++)
		   for(int j=0;j<x;j++)
		   {
		   	    cin >> ti[i][j];
		   }
        int sum=0;
        for(int i=0;i<y;i++)
		   for(int j=0;j<x;j++)
              if(bfs(i,j))
              {
                  sum++;
              }
        cout << sum << endl;
	}
}

C++: #define _USE_MATH_DEFINES
#define INF 100000000

#include <iostream>
#include <sstream>
#include <cmath>
#include <cstdlib>
#include <algorithm>
#include <queue>
#include <stack>
#include <limits>
#include <map>
#include <string>
#include <cstring>
#include <set>
#include <deque>
#include <bitset>
#include <list>
#include <cctype>
#include <utility>

using namespace std;

typedef long long ll;
typedef pair <int,int> P;
typedef pair <int,P> PP;

static const double EPS = 1e-8;

int stage[50][50];

void dfs(int x,int y,int w,int h){
	stage[y][x] = 0;
	for(int tx=-1;tx<=1;tx++){
		for(int ty=-1;ty<=1;ty++){
			int dx = x + tx;
			int dy = y + ty;
			if(dx < 0 || dx >=w || dy < 0 || dy >= h) continue;

			if(stage[dy][dx]==1){
				dfs(x+tx,y+ty,w,h);
			}
		}
	}
}

int main(){
	int w,h;
	while(~scanf("%d %d",&w,&h)){
		if(w==h && h==0) break;
		for(int y=0;y<h;y++){
			for(int x=0;x<w;x++){
				scanf("%d",(*(stage+y)+x));
			}
		}

		int res=0;
		for(int y=0;y<h;y++){
			for(int x=0;x<w;x++){
				if(stage[y][x]==1){
					dfs(x,y,w,h);
					res++;
				}
			}
		}

		printf("%d\n",res);
	}
}

C++: #pragma GCC optimize ("O3")
#include <iostream>
#include <iomanip>
#include <istream>
#include <ostream>
#include <sstream>
#include <iterator>
#include <vector>
#include <algorithm>
#include <queue>
#include <deque>
#include <list>
#include <stack>
#include <map>
#include <unordered_map>
#include <set>
#include <bitset>
#include <utility>
#include <cmath>
#include <cstdio>
#include <cstring>
#include <string>
#include <ctime>
#include <cctype>
#include <cstdlib>
#define IINF 10e8
#define INF 1<<30
#define MOD 1000000007
#define mod 998244353
#define REP(i, a, n) for (ll i = a; i < (ll)(n); i++)
#define REPE(i, a, n) for (ll i = a; i <= (ll)(n); i++)
#define Endl endl
#define fi first
#define se second
#define pb push_back
#define mp make_pair
#define eb emplace_back
#define mmax(x,y)(x>y?x:y)
#define mmin(x,y)(x<y?x:y)
#define chmax(x,y) x=mmax(x,y)
#define chmin(x,y) x=mmin(x,y)
#define all(x) (x).begin(),(x).end()
#define siz(x) (ll)(x).size()
#define PI acos(-1.0)
using namespace std;
typedef long long int ll;
typedef unsigned long long int ull;
typedef long double ld;
typedef pair<int,int>Pin;
typedef pair<ll,ll>Pll;
template<class T> using V=vector<T>;
long long GCD(long long a, long long b) {return b?GCD(b,a%b):a;}
long long LCM(long long a, long long b) {return a/GCD(a,b)*b;}
int dx[4]={-1,0,1,0};
int dy[4]={0,-1,0,1};
int ddx[8]={-1,0,1,0,1,1,-1,-1};
int ddy[8]={0,-1,0,1,1,-1,1,-1};
ll cmp(pair<ll,ll>a,pair<ll,ll> b){
        if(a.se!=b.se)
        return a.se<b.se;
        else
        return a.fi<b.fi;
}
//----------------------------------------------------------------------
int h,w;
int c[55][55];
bool color[55][55];
int ans=0;

//----------------------------------------------------------------------
int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);
    //-------------------------------  
    //ll begin_time=clock();
    //-------------------------------
    cin>>w>>h;
while(w&&h){
    memset(color,0,sizeof(color));
    ans=0;
    for(int i=0;i<h;i++){
        for(int j=0;j<w;j++){
            cin>>c[i][j];
        }
    }

    for(int i=0;i<h;i++){
        for(int j=0;j<w;j++){
            //cout<<i<<" "<<j<<" "<<color[i][j]<<" "<<c[i][j]<<Endl;
            if(color[i][j])continue;
            if(c[i][j]==0)continue;
            queue<Pin>q;
            ans++;
            q.push(mp(i,j));
            while(!q.empty()){
                Pin tmp=q.front();q.pop();
                int x=tmp.fi;int y=tmp.se;
                for(int i=0;i<8;i++){
                    int nx=x+ddx[i];
                    int ny=y+ddy[i];
                    //cout<<nx<<" "<<ny<<endl;
                    if(nx>=0&&ny>=0&&nx<h&&ny<w){
                        if(color[nx][ny])continue;
                        if(c[nx][ny]==0)continue;
                        color[nx][ny]=1;
                        q.push(mp(nx,ny));
                    }
                }
            }
        }
    }
    cout<<ans<<Endl;
    cin>>w>>h;
}
    //-------------------------------  
    //ll end_time=clock();cout<<"time="<<end_time-begin_time<<"ms"<<endl;
    //-------------------------------
    return 0;
}
//----------------------------------------------------------------------