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 <string>
#include <vector>
#include <queue>
#include <set>
#include <map>
#include <utility>
#include <stack>
#include <numeric>
#include <algorithm>
#include <stdio.h>
#include <bitset>
#include <complex>
#include <iomanip>
using namespace std;
//using ll = long long;
#define MM 1000000000
#define MOD MM+7
#define pi pair<int32,int32>
#define pl pair<int64,int64>
#define chmax(a,b) (a<b ? a=b:0)
#define chmin(a,b) (a>b ? a=b:0)
const long double PI = acos(-1);
const long long INF = 1e15;
int dx[8] = {-1,0,1,0,-1,-1,1,1};
int dy[8] = {0,-1,0,1,-1,1,1,-1};
template<typename T>
T GCD(T u,T v){
    return v ? GCD(v,u%v) : u;
}
int c[50][50];
int visited[50][50];
void init(int h,int w){
    for(int i = 0; i < 50; i++){
        for(int j = 0; j < 50; j++){
            visited[i][j] = false;
            c[i][j] = 0;
        }
    }
}
void dfs(int h,int w,int H,int W){
    visited[h][w] = true;
    for(int i = 0; i < 8; i++){
        int ny = h+dy[i];
        int nx = w+dx[i];
        if (0 <= ny && ny < H && 0 <= nx && nx < W && visited[ny][nx] == false && c[ny][nx] == 1){
            dfs(ny,nx,H,W);
        }
    }
    return;
}
int main(){
    vector<int> ans(0);
    for(;;){
        int H,W; cin >> W >> H;
        if(H == 0 && W == 0) break;
        init(H,W);
        for(int h = 0; h < H; h++){
            for(int w = 0; w < W; w++){
                cin >> c[h][w];
            }
        }
        int cnt = 0;
        for(int h = 0; h < H; h++){
            for(int w = 0; w < W; w++){
                if (c[h][w] == 1 && visited[h][w] == false){
                    dfs(h,w,H,W);
                    cnt++;
                }
            }
        }
        /* 
        for(int i = 0; i < H; i++){
            for(int j = 0; j < W; j++){
                cout << visited[i][j] << " ";
            }
            cout << endl;
        }
        */
        ans.push_back(cnt);
    }
    for(int i = 0; i < ans.size(); i++){
        cout << ans[i] << endl;
    }
}

C++: #include<iostream>
#include<algorithm>
#include<cmath>
#include<map>
#include<stdio.h>
#include<vector>
using namespace std;
#define int long long
#define double long double
#define rep(s,i,n) for(int i=s;i<n;i++)
#define c(n) cout<<n<<endl;
#define ic(n) int n;cin>>n;
#define sc(s) string s;cin>>s;
#define mod 1000000007
#define inf 1000000000000000007
#define f first
#define s second
#define mini(c,a,b) *min_element(c+a,c+b)
#define maxi(c,a,b) *max_element(c+a,c+b)
#define P pair<int,int>
//printf("%.12Lf\n",);
int keta(int x){
	rep(0,i,30){
		if(x<10){
			return i+1;
		}
		x=x/10;
	}
}
int gcd(int x,int y){
	int aa=x,bb=y;
	rep(0,i,1000){
		aa=aa%bb;
		if(aa==0){
			return bb;
		}	
		bb=bb%aa;
		if(bb==0){
			return aa;
		}
	}
}	
int lcm(int x,int y){
	int aa=x,bb=y;
	rep(0,i,1000){
		aa=aa%bb;
		if(aa==0){
			return x/bb*y;
		}	
		bb=bb%aa;
		if(bb==0){
			return x/aa*y;
		}
	}
}
bool p(int x){
	if(x==1)return false;
	rep(2,i,sqrt(x)+1){
		if(x%i==0&&x!=i){
			return false;
		}
	}	
	return true;
}
int max(int a,int b){
	if(a>=b)return a;
	else return b;
}
int min(int a,int b){
	if(a>=b)return b;
	else return a;
}	
int n2[41];		
int nis[41]; 
int nia[41];
int mody[41];
int nn;
int com(int n,int y){
	int ni=1;
	for(int i=0;i<41;i++){
		n2[i]=ni;
		ni*=2;
	}
	int bunsi=1,bunbo=1;
	rep(0,i,y)bunsi=(bunsi*(n-i))%mod;
	rep(0,i,y)bunbo=(bunbo*(i+1))%mod;
	mody[0]=bunbo;
	rep(1,i,41){
		bunbo=(bunbo*bunbo)%mod;
		mody[i]=bunbo;
	}
	rep(0,i,41)nis[i]=0;
	nn=mod-2;
	for(int i=40;i>=0;i-=1){
		if(nn>n2[i]){
			nis[i]++;
			nn-=n2[i];
		}
	}
	nis[0]++;
	rep(0,i,41){
		if(nis[i]==1){
			bunsi=(bunsi*mody[i])%mod;
		}
	}
	return bunsi;
}
int yakuwa(int n){
	int sum=0;
	rep(1,i,sqrt(n+1)){
		if(n%i==0)sum+=i+n/i;
		if(i*i==n)sum-=i;
	}
	return sum;
}	
bool integer(double n){
	if(n==long(n))return true;
	else return false;	
}
int pow(int b,int a){	
	int aa=1;
	rep(0,i,a)aa*=b;	
	return aa;
}
int sankaku(int a){
	return a*(a+1)/2;
} 
bool search(int x){
	int n;
	int a[n];
	int l=0,r=n;
	while(r-l>=1){
		int i=(l+r)/2;
		if(a[i]==x)return true;
		else if(a[i]<x)l=i+1;
		else r=i;
	}
	return false;
}
int h,w;
char c[55][55];
void dfs(int x,int y){
	c[x][y]='0';
	for(int i=-1;i<=1;i++)for(int j=-1;j<=1;j++){
		int nx=x+i;
		int ny=y+j;
		if(0<=nx&&nx<w&&0<=ny&&ny<h&&c[nx][ny]=='1')dfs(nx,ny);
	}
	return ;
}	
signed main(){
	bool a=true;
	while(a){
		int ans=0;
		cin>>h>>w;
		if(h==0&&w==0)return 0;
		rep(0,i,w)rep(0,j,h)cin>>c[i][j];
		rep(0,i,w)rep(0,j,h){
			if(c[i][j]=='1'){
				dfs(i,j);
				ans++;
			}
		}
		c(ans)
	}	
}

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, nw = w + dw;

      if (nh < 0 || nh >= H || nw < 0 || nw >= W) continue;
      if (field[nh][nw] == 0) continue;

      dfs(nh, nw);
    }
  }
}

int main() {
  while (cin >> W >> H) {
    if (H == 0 || W == 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;
  }
}