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>

#define rep(i, n) for(int i = 0 ; i < n ; i++)

using namespace std;

int area[50][50], cnt = 0;
int w, h;

void dfs(int x ,int y)
{
  area[x][y] = 0;

  for(int dx = -1 ; dx <= 1 ; dx++){
    for(int dy = -1 ; dy <= 1 ; dy++){
      int nx = x + dx, ny = y + dy;

      if(0 <= nx && nx < w && 0 <= ny && ny < h && area[nx][ny] == 1){
	dfs(nx, ny);
      }
    }
  }
}

int main()
{
  while(true){
    cin >> w >> h;
    if(w == 0 && h == 0) break;

    rep(j, h){
      rep(i, w){
	cin >> area[i][j];
      }
    }

    rep(i, w){
      rep(j, h){
	if(area[i][j] == 1){
	  dfs(i, j);
	  cnt++;
	}
      }
    }
    
    cout << cnt << '\n';
    cnt = 0;
  }
}

C++: #include <iostream>
#include <vector>
using namespace std;
int ans;
int w, h;
//?§???????
vector<int> vx = { -1, 0, 1, -1, 1, -1, 0, 1 };
vector<int> vy = { 1, 1, 1, 0, 0, -1, -1, -1 };
vector<vector<int>> map;
void Search(int i,int j){
	//??¨????????????????????§??????
	for (int m = 0; m < vx.size(); m++){
		int x = j + vx[m];
		int y = i + vy[m];
		if (x >= 0 && x < w &&
			y >= 0 && y < h){
			if (map[y][x] == 1){
				map[y][x] = map[i][j];
				Search(y,x);
			}
		}
	}
}

int main(){
	while (1){
		cin >> w >> h;
		if (w == 0 && h == 0) break;
		ans = 1;
		map = vector<vector<int>>(h,vector<int>(w));
		//???????????????
		for (int i = 0; i < h; i++){
			for (int j = 0; j < w; j++){
				cin >> map[i][j];
			}
		}

		//??¢?´¢
		for (int i = 0; i < h; i++){
			for (int j = 0; j < w; j++){
				if (map[i][j] != 1) continue;
				ans++;
				Search(i,j);
			}
		}
		cout << --ans << endl;
	}
	return 0;
}

C++: #include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<ll,ll> pll;

ll w,h;
vector<vector<ll>> ans(50,vector<ll> (50,-1));
vector<vector<ll>> maze(50,vector<ll> (50));

vector<ll> idx={1,0,-1,0,1,1,-1,-1};
vector<ll> idy={0,1,0,-1,1,-1,1,-1};

bool dfs(ll th,ll tw,ll n) {
  if(ans[th][tw]<0&&maze[th][tw]==1) {
    ans[th][tw]=n;
    for(ll i=0;i<8;i++) {
      ll nh=th+idy[i];
      ll nw=tw+idx[i];
      if(nh>-1&&nh<h&&nw>-1&&nw<w) {
        dfs(nh,nw,n);
      }
    }
    return true;
  }
  else {
    return false;
  }
}

int main() {
  while(1) {
    cin >> w >> h;
    if(w==0&&h==0) {
      return 0;
    }
    for(ll i=0;i<h;i++) {
      for(ll j=0;j<w;j++) {
        cin >> maze[i][j];
        ans[i][j]=-1;
      }
    }
    ll count=0;
    for(ll i=0;i<h;i++) {
      for(ll j=0;j<w;j++) {
        if(dfs(i,j,count)) {
          count++;
        }
      }
    }
    cout << count << endl;
  }
}

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

int w,h;
int mp[50][50];

void rec(int y,int x){
	if(mp[y][x]==0)return;
	mp[y][x]=0;
	if(x+1<w)rec(y,x+1);
	if(y+1<h)rec(y+1,x);
	if(x-1>=0)rec(y,x-1);
	if(y-1>=0)rec(y-1,x);
	if(x+1<w&&y-1>=0)rec(y-1,x+1);
	if(y+1<h &&y+1<h)rec(y+1,x+1);
	if(x-1>=0&&y+1<h)rec(y+1,x-1);
	if(y-1>=0&&x-1>=0)rec(y-1,x-1);
}

int main(){
	int x,y,ret;
	while(cin >> w >> h && w && h){
		ret = 0;
		for(int i=0;i<h;i++){
			for(int j=0;j<w;j++){
				cin >> mp[i][j];
			}
		}
		for(int i=0;i<h;i++){
			for(int j=0;j<w;j++){
				if(mp[i][j]){
					rec(i,j);
					ret++;
				}
			}
		}
		cout << ret << endl;
	}
	return 0;
}

C++: #include <iostream>

#define rep(i, n) for(int i = 0 ; i < n ; i++)

using namespace std;

int area[50][50], cnt = 0;
int w, h;

void dfs(int x ,int y)
{
  area[x][y] = 0;

  for(int dx = -1 ; dx <= 1 ; dx++){
    for(int dy = -1 ; dy <= 1 ; dy++){
      int nx = x + dx, ny = y + dy;

      if(0 <= nx && nx < w && 0 <= ny && ny < h && area[nx][ny] == 1){
	dfs(nx, ny);
      }
    }
  }
}

int main()
{
  while(true){
    cin >> w >> h;
    if(w == 0 && h == 0) break;

    rep(i, h){
      rep(j, w){
	cin >> area[i][j];
      }
    }

    rep(i, w){
      rep(j, h){
	if(area[i][j] == 1){
	  dfs(i, j);
	  cnt++;
	}
      }
    }
    
    cout << cnt << '\n';
    cnt = 0;
  }
}

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

int main(){
  bool map[52][52];
  int w,h;

  while(cin >> w >> h && w>0 && h>0){
    for(int i=0;i<52;i++){
      for(int j=0;j<52;j++)
        map[i][j]=false;
    }

    int land=0;

    for(int i=1;i<=h;i++){
      for(int j=1;j<=w;j++){
        int c;
        cin >> c;
        if(c==1) map[i][j]=true;
        land++;
      }
    }

    int visited=0,cnt=0;
    queue<int> cur;
    int d[8]={-w-3,-w-2,-w-1,-1,1,w+1,w+2,w+3}

    while(visited<land){
      cnt++;
      for(int i=0;i<(w+2)*(h+2);i++){
        if(map[i/(w+2)][i%(w+2)]){
          map[i/(w+2)][i%(w+2)]=false;
          visited++;
          cur.push(i);
          break;
        }
      }
      while(!cur.empty()){
        for(int i=0;i<8;i++){
          if(map[(cur.front()+d[i])/(w+2)][(cur.front()+d[i])%(w+2)]){
            map[(cur.front()+d[i])/(w+2)][(cur.front()+d[i])%(w+2)]=false;
            visited++;
            cur.push(cur.front()+d[i]);
          }
        }
        cur.pop();
      }
    }

    cout << cnt << endl;
  }

  return 0;
}