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 <bits/stdc++.h>

using namespace std;

#define loop(n) for(int lp=0; lp<(n); lp++)
#define ascent(i, a, b)  for(int (i)=(a); (i)<(b); (i)++)
#define descent(i, a, b) for(int (i)=(a); (i)<(b); (i)--)

int w, h;

int flg[60][60];
int m[60][60];

//int dx[4] = {-1, 0, 1, 0};
//int dy[4] = {0, 1, 0, -1};

stack<pair<int, int> > land;
void island(int x, int y) {
  if(x < 0 || w <= x || y < 0 || h <= y) return;

  land.push(make_pair(x, y));

  while(!land.empty()) {
    pair<int, int> p = land.top(); land.pop();

    int _x = p.first;
    int _y = p.second;
    //cout << " " << _x << "," << y << endl;

    if(m[_y][_x]) {
      //     cout << " " << x << "," << y << " is island" << endl;
      flg[_y][_x] = 1;
    }

    for(int dx = -1; dx <= 1; dx ++) {
      for(int dy = -1; dy <= 1; dy ++) {
	if(dx == 0 && dy == 0) continue;
	if(!flg[_y+dy][_x+dx] && 0 <= _x+dx && _x+dx < w && 0 <= _y+dy && _y+dy < h) {
	  //	    cout << "  " << _x+dx << "," << _y+dy << endl;
	  if(m[_y+dy][_x+dx]) {
	    land.push(make_pair(_x+dx, _y+dy));
	  }
	}
      }
    }
  }
}

int bfs() {
  int ans = 0;
  //  flg[0][0] = 1;

  ascent(y, 0, h) {
    ascent(x, 0, w) {
      if(!flg[y][x]) {
	flg[y][x] = 1;
	if(m[y][x]) {
	  ans ++;
	  //	  cout << " " << x << "," << y << endl;
	  island(x, y);
	}
      }
    }
  }

  return ans;
}

int main() {
  while(cin >> w >> h, w) {
    ascent(i, 0, h) {
      ascent(j, 0, w) {
	cin >> m[i][j];
	flg[i][j] = 0;
      }
    }

    cout << bfs() << endl;
  }
  return 0;
}

C++: #include <iostream>

using namespace std;

int c[50][50],w,h;
int dx[8]={-1,-1,-1,0,0,1,1,1};
int dy[8]={-1,0,1,-1,1,-1,0,1};
void dfs(int y,int x){
  if(c[y][x]){
    c[y][x]=0;
    int i;
    for(i=0;i<8;i++){
      if(y+dy[i]>=0 && y+dy[i]<h && x+dx[i]>=0 && x+dx[i]<w && c[y+dy[i]][x+dx[i]])
      dfs(y+dy[i],x+dx[i]);
    }
  }
  return;
}

int main(){
  int i,j,ans;
  cin >> w >> h;
  while(1){
    ans=0;
    if(w+h==0)break;
    //for(i=0;i<50;i++)for(j=0;j<50;j++)c[i][j]=0;
    for(i=0;i<h;i++){
      for(j=0;j<w;j++)cin >> c[i][j];
    }
    for(i=0;i<h;i++){
      for(j=0;j<w;j++)if(c[i][j]){
        dfs(i,j);
        ans++;
      }
    }
    cout << ans << endl;
    cin >> w >> h;
  }
  return 0;
}

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

int a[50][50];

void dfs(int j,int i){
  
  a[j][i]=0;
for(int k=-1 ; k <= 1 ; k++){
    for(int l=-1 ; l <= 1 ; l++){
      if( l== 0 && k== 0 )continue;
      if( (0 <= j+l && j+l <= 50)&&(0<=i+k && i+k <= 50)){
      if(a[j+l][i+k])dfs(j+l,i+k);
      }
    }
 }
} 
int main(){
  
  int w,h,counter=0;
  
  while(1){
    
    cin >>w>>h;
    
    if( w == 0 && h == 0 )break;
    
    counter=0;
    
    for(int i=0 ; i < h ; i++){
      for(int j=0 ; j < w ; j++){
	cin >>a[j][i];
      }
    }
    
    for(int i=0 ; i < h ; i++){
      for(int j=0 ; j < w ; j++){
	
	if(a[j][i]){
	  dfs(j,i);
	  counter++;
	}
	
      }
    }
    
    cout<<counter<<endl;
    
  }
  
  return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
using ll=long long;
typedef pair<int,int> P;
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }
int w,h;
int nx,ny;
void dfs(vector<vector<int>> &G,int a,int b){
     if(0>nx|| nx>=h || 0>ny|| ny>=w) return ;
     if( G.at(nx).at(ny)==0) return ; 
     G.at(a).at(b)=0;
    for(int k=-1;k<=1;k++){
        for(int s=-1;s<=1;s++){
            nx=a+k;
            ny=b+s;
            dfs(G,nx,ny);
        }
    }
    return ;
}
 
 
 
int main(){
    cin>>w>>h;
    vector<vector<int>>G(h,vector<int>(w));
    for(int i=0;i<h;i++){
        for(int j=0;j<w;j++){
            cin>>G.at(i).at(j);
        }
    }
    int count=0;
    for(int i=0;i<h;i++){
        for(int j=0;j<w;j++){
            if(G.at(i).at(j)==1){
                count++;
                dfs(G,i,j);
            }
        }
    }
cout<<count<<endl;
}

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

using namespace std;

#define llong long long 
int w,h;
int sum = 0;
int area[50][50];
int nw[8] = {0, 1, 1, 1, 0, -1, -1, -1};
int nh[8] = {1, 1, 0, -1, -1, -1, 0, 1};

void solve(int h, int w){
	if(area[h][w] == 0)return;
	area[h][w] == 0;
	for(int i = 0; i < 8; i++){
		int sh = h + nh[i];
		int sw = w + nw[i];
		solve(sh, sw);
	}
	return;
}

int main(){
	fill_n(*area, 50 * 50, 0);
	cin >> w >> h;
	for(int i = 0; i < h; i++){
		for(int j = 0; j < w; j++){
			cin >> area[i][j];
		}
	}	

	for(int i = 0; i < h; i++){
		for(int j = 0; j < w; j++){
			if(area[i][j] == 1){
				sum++;
				solve(i, j);
			}
		}
	}

	cout << sum << endl;
	return 0;
}

C++: #include<iostream>
#include<string>
#include<algorithm>
#include<vector>
#include<map>
#include<queue>
#include<cstdio>
#include<cstring>
using namespace std;

#define rep(i,n) for(int i=0;i<n;i++)
#define REP(n) rep(i,n)
#define all(n) n.begin(),n.end()

const int MAXW = 52, MAXH = 52, RIKU = 1, UMI = 0;

int tile[MAXH][MAXW];
int dx[] = {-1, 0, 1, -1, 1, -1, 0, 1};
int dy[] = {-1, -1, -1, 0, 0, 1, 1, 1};
int w, h;

int solve(int x, int y)
{
    if(tile[x][y] == RIKU)
    {
        tile[x][y] = UMI;
        
        REP(8)if( x+dx[i]>=0 && x+dx[i] < w && y+dy[i] >= 0 && y+dy[i] < h)
            solve(x+dx[i], y+dy[i]);

        return 1;
    }
    return 0;
}

int main()
{
    while(cin >> w >> h && (w || h))
    {
        memset(tile, 0, sizeof(tile));
        rep(j,h)rep(i,w) cin >> tile[i][j];

        int ans = 0;
        rep(j,h)rep(i,w) ans += solve(i,j);

        cout << ans << endl;
    }
    return 0;
}