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<stack>
#include<vector>
#include<map>

using namespace std;

pair<int, int> serch_land(vector<vector<int> >& maps){
  for(int i = 0; i < maps.size(); i++){
    for(int j = 0; j < maps[i].size(); j++){
      if(maps[i][j] == 1){
        return make_pair(i, j);
      }
    }
  }
  return make_pair(-1, -1);
}

void delete_land(vector<vector<int> >& maps, pair<int, int> start){
  int dh[8] = {1, 1, 1, 0, 0, -1, -1, -1};
  int dw[8] = {1, 0, -1, 1, -1, 1, -1, 0};

  stack< pair<int, int> > s;
  s.push(start);
  pair<int, int> cur;
  maps[start.first][start.second] = 0;

  while(!s.empty()){
    cur = s.top();
    s.pop();

    for(int i = 0; i < 8; i++){
      if(maps[cur.first + dh[i]][cur.second + dw[i]] == 1){
        maps[cur.first + dh[i]][cur.second + dw[i]] = 0;
        pair<int, int> next = make_pair(cur.first + dh[i], cur.second + dw[i]);
        s.push(next);
      }
    }
  }
}

int main(){
  int w, h;

  while(cin >> w >> h, !(w == 0 && h == 0)){
    vector<vector<int> > maps = vector<vector<int> >(h+2, vector<int>(w+2));
    pair<int, int> land;

    for(int i = 0; i < h+2; i++){
      for(int j = 0; j < w+2; j++){
        if(i == 0 || j == 0 || i == h+1 || j == w+1){
          maps[i][j] = 0;
        }else{
          cin >> maps[i][j];
        }
      }
    }


    int cnt = 0;
    while(land = serch_land(maps), land.first != -1){
      cnt++;
      delete_land(maps, land);
    }
    cout << cnt << endl;

  }
}

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

typedef long long LL;

//container util
//------------------------------------------
#define ALL(a)  (a).begin(),(a).end()
#define RALL(a) (a).rbegin(), (a).rend()
#define PB push_back
#define MP make_pair
#define DECIM8  fixed<<setprecision(8) 
#define SZ(a) int((a).size())
#define SORT(c) sort((c).begin(),(c).end())

//repetition
//------------------------------------------
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n)  FOR(i,0,n)

//constant
//--------------------------------------------
const double EPS = 1e-10;
const double PI  = acos(-1.0);

//clear memory
#define CLR(a) memset((a), 0 ,sizeof(a))

using namespace std;
int f[64][64];

int del(int i,int j)
{
  if(i<0||j<0) return 0;
  if(f[i][j]){
    f[i][j]=0;
    REP(di,3) REP(dj,3)
      del(i+di-1,j+dj-1);
    return 1;
  }
  else return 0;
}
int main(void)
{
  for(;;){
    int n,m;
    cin >> n >> m;
    if(!n&&!m) return 0;
    REP(j,m){
      REP(i,n)
	cin >> f[i][j];
    }
    int answer=0;
    REP(j,m){
      REP(i,n)
	answer+=del(i,j);
    }
    cout << answer << endl;
  }
}

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

int dx[] = {0, 0, 1, -1, 1, -1, 1, -1}, dy[] = {1, -1, 0, 0, 1, -1, -1, 1}, W, H;
bool mem[50][50];

int bfs(int sx, int sy)
{
  if(!mem[sy][sx])
    return 0;
  queue<int> q;
  q.push(sx);
  q.push(sy);
  while(!q.empty())
  {
    int x = q.front(); q.pop();
    int y = q.front(); q.pop();
    mem[y][x] = 0;
    for(int i = 0; i < 8; i++)
    {
      int tx = x + dx[i];
      int ty = y + dy[i];
      if(tx >= 0 && tx < W && ty >= 0 && ty < H && mem[ty][tx])
      {
        q.push(tx);
        q.push(ty);
      }
    }
  }
  return 1;
}

int main()
{
loop:
  int ans = 0;
  for(int y = 0; y < 50; y++)
    for(int x = 0; x < 50; x++)
      mem[y][x] = 0;
  cin >> W >> H;
  if(!W)
    return 0;
  for(int y = 0; y < H; y++)
    for(int x = 0; x < W; x++)
      cin >> mem[y][x];
  for(int y = 0; y < H; y++)
    for(int x = 0; x < W; x++)
      ans += bfs(x, y);
  cout << ans << endl;
  goto loop;
}

C++: #include <bits/stdc++.h>
using namespace std;

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

void dfs(int h, int w)
{
    field[h][w] = 0;
    
    for(int dh = -1; dh <= 1; dh++)
    {
        for(int dw = -1; dw <= 1; dw++)
        {
            int nh = h + dh;
            int nw = w + dw;
            
            if((nh >= H)||(nh < 0)||(nw >= W)||(nw < 0)) continue;
            if(field[nh][nw] == 0) continue;
            
            dfs(nh,nw);
        }
    }
}



int main()
{
    while(cin >> W >> H)
    {
        if((W == 0)||(H == 0)) break;
        field.assign(H,vector<int>(W,0));
        for(int h = 0; h < H; h++)
        {
            for(int w = 0; w < W; w++)
            {
                cin >> field[h][w];
            }
        }
        
        int count = 0;
        for(int h = 0; h < H; h++)
        {
            for(int w = 0; w < W; w++)
            {
                if(field[h][w] == 0) continue;
                dfs(h,w);
                count++;
            }
        }
        cout << count << endl;
    }
}

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

int m[51][51];
bool v[51][51];
int h,w;
int dx[8]={-1,-1,0,1,1,1,0,-1};
int dy[8]={0,-1,-1,-1,0,1,1,1};
void dfs(int x,int y){
    if(v[y][x])return;
    v[y][x]=1;
    for(int i=0;i<8;i++){
        int nx=x+dx[i];
        int ny=y+dy[i];
        if(nx>=0&&nx<w&&ny>=0&&ny<h&&!v[ny][nx]&&m[ny][nx]){
            dfs(nx,ny);
        }
    }
}
int main(){
    while(cin>>w>>h,h){
        int c=0;
        for(int i=0;i<h;i++){
            for(int j=0;j<w;j++){
                cin>>m[i][j];
                v[i][j]=0;
            }
        }
        for(int i=0;i<h;i++){
            for(int j=0;j<w;j++){
                if(!v[i][j]&&m[i][j]){
                    dfs(j,i);
                    c++;
                }
            }
        }
        cout<<c<<endl;
    }
}