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<queue>
using namespace std;

#define inRange(x,a,b) (a <= x && x < b)
int di[8] = {0,0,1,-1,1,1,-1,-1};
int dj[8] = {1,-1,0,0,1,-1,1,-1};

int main(){
    int w, h;
    while(cin >> w >> h, w+h){
        char mat[h][w];
        for(int i = 0; i < h*w; i++)    cin >> mat[i/w][i%w];
        int ans = 0;
        for(int i = 0; i < h; i++){
            for(int j = 0; j < w; j++){
                if(mat[i][j] == '0')    continue;
                ans++;
                mat[i][j] = '0';
                queue<pair<int,int>> q;
                q.push({i,j});
                while(!q.empty()){
                    auto p = q.front(); q.pop();
                    int x = p.first, y = p.second;
                    for(int k = 0; k < 8; k++){
                        int nx = x+di[k], ny = y+dj[k];
                        if(inRange(nx,0,h)&&inRange(ny,0,w)&&mat[nx][ny]=='1'){
                            mat[nx][ny] = '0';
                            q.push({nx,ny});
                        }
                    }
                }
            }
        }
        cout << ans << endl;
    }
    return 0;
}

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

#define W 50
#define H 50

using namespace std;
void dfs(int w, int h);
int map[H][W];
int dy[8] = {1,1,0,-1,-1,-1,0,1}, dx[8] = {0,-1,-1,-1,0,1,1,1};
int w,h;

int main(){
  int i = 0,j = 0,is=0;
  cin >> w >> h;

  while(w != 0 && h != 0){
    for(i = 0;i < h;i++){
      for(j = 0;j<w;j++){
	cin>>map[i][j];
      }
    }
    i = j = 0;
    is = 0;
    while(i <= h-1  && j <= w-1){
      if(map[i][j] == 1){
	dfs(i,j);
	cout << "dfs end" << endl;
	is++;
      }
      i++;
      if(i == h){
	i = 0;
	j++;
      }
    }
    cout <<"the number of island is " << is << endl;
    cin >> w >> h;
  }
  return 0;
}

void dfs(int x,int y){
  cout << "x is " << x << " y is " << y <<endl;
  int i = 0;
  map[x][y] = 0;
  for(i = 0;i < 8; i++){
    if(x + dx[i] > -1 && y + dy[i] > -1 && x + dx[i] < h && y + dy[i] < w){
      if(map[x + dx[i]][y + dy[i]] == 1){
	dfs(x + dx[i],y + dy[i]);
      }
    }
  }
}

C++: #include<iostream>
#include<cstdio>
#include<algorithm>
#include<cmath>
#include<string>
#include<vector>
#include<list>
#include<set>
#include<map>
#include<queue>
#include<stack>
#include<cctype>
#include<climits>
#include<bitset>
#define ld long double
#define ll long long int
#define ull unsigned long long int
#define rep(i,n) for(i=0;i<n;i++)
#define fin(ans) cout<<(ans)<<endl
#define INF INT_MAX
#define vi vector<int>
#define vc vector<char>
#define vs vector<string>
#define vpii vector<pair<int,int> >
#define vvi vector<vector<int> >
#define vvc vector<vector<char> >
#define vvs vector<vector<string> >
#define P 1000000007
using namespace std;
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;}
const long long LLINF=1LL<<60;
//set<int>::iterator it;
//|\_
//g++ -std=c++1z temp.cpp
//./a.out

vvi v(50,vi(50,-2));

bool dfs(int x,int y,int count,int h,int w){
    
    if(v[y][x]>=0)return false;
    v[y][x]=count;
    bool t=true;
    if(x+1<w&&v[y][x+1]==-1){
        t=dfs(x+1,y,count,h,w);
    }
    if(x-1>=0&&v[y][x-1]==-1){
        t=dfs(x-1,y,count,h,w);
    }
    if(y+1<h&&v[y+1][x]==-1){
        t=dfs(x,y+1,count,h,w);
    }
    if(y-1>=0&&v[y-1][x]==-1){
        t=dfs(x,y-1,count,h,w);
    }///////
    if(x+1<w&&y+1<h&&v[y+1][x+1]==-1){
        t=dfs(x+1,y+1,count,h,w);
    }
    if(x-1>=0&&y-1>=0&&v[y-1][x-1]==-1){
        t=dfs(x-1,y-1,count,h,w);
    }
    if(y+1<h&&x-1>=0&&v[y+1][x-1]==-1){
        t=dfs(x-1,y+1,count,h,w);
    }
    if(y-1>=0&&x+1<w&&v[y-1][x+1]==-1){
        t=dfs(x+1,y-1,count,h,w);
    }
    if(t) return true;
    else return false;
}

int main(void){ios::sync_with_stdio(false);cin.tie(0);
//////////////////////////////////////////////////////
    int w,h,i,j;
    while(1){
        cin>>w>>h;
        if(w==0&&h==0)break;
        int count=1,x,y;
        rep(i,50)rep(j,50)v[i][j]=-2;
        rep(i,h)rep(j,w){
            cin>>v[i][j];
            v[i][j]*=-1;
        }
        bool c;
        for(y=0;y<h;y++){
            for(x=0;x<w;x++){
                c=dfs(x,y,count,h,w);
                if(c)count++;
            }
        }
        set<int> s;
        for(y=0;y<h;y++){
            for(x=0;x<w;x++){
                if(v[y][x]>0)s.insert(v[y][x]);
            }
        }
        cout<<s.size()<<endl;
        /*
        for(y=0;y<h;y++){
            for(x=0;x<w;x++){
                cout<<v[y][x]<<" ";
            }
            cout<<endl;
        }*/
    }
    

//////////////////////////////////////////////////////
return 0;}