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<cstring>
#include<queue>
using namespace std;

int counter=2;
int Map[50][50];
int x[8] = {0,0,1,-1,1,1,-1,-1};
int y[8] = {-1,1,0,0,1,-1,1,-1};
int w,h;

void bfs(int xx,int yy){
  Map[yy][xx]=counter;
  queue<int> q;
  int pos = yy*w+xx;
  q.push(pos);
  while(!q.empty()){
    pos=q.front();
    q.pop();
    yy=pos/w;
    xx=pos%w;
    for(int k=0;k<8;k++){
      int a=xx+x[k];
      int b=yy+y[k];
      if(a < 0 || a >= w || b < 0 || b >= h) continue;
      if(Map[b][a]==1){
	Map[b][a]=counter;
	q.push(b*w+a);
      }
    }
  }
}

int main(){
  while(cin>>w>>h , w+h){
    counter=2;
    memset(Map,0,sizeof(Map));
    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){
	  bfs(j,i);
	  counter++;
	  //     	  cout<<" i = "<<i<<" j = "<<j<<endl;
	}
      }
    }
    cout<<counter-2<<endl;
  }
  return 0;
}

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

#define	mp	make_pair

using namespace std;

typedef	pair<int,int>	pii;

const int dx[]={1,1,0,-1,-1,-1,0,1},dy[]={0,-1,-1,-1,0,1,1,1};
int field[50][50];
bool visited[50][50];

int main(){
	for(int w,h;scanf("%d%d",&w,&h),w;){
		for(int i=0;i<h;i++)for(int j=0;j<w;j++){
			scanf("%d",field[i]+j);
			visited[i][j]=false;
		}

		int cnt=0;
		for(int i=0;i<h;i++)for(int j=0;j<w;j++){
			if(field[i][j]==1 && !visited[i][j]){
				visited[i][j]=true;
				queue<pii> qu;	qu.push(mp(i,j));
				while(!qu.empty()){
					pii a=qu.front();	qu.pop();
					for(int k=0;k<8;k++){
						int xx=a.second+dx[k],yy=a.first+dy[k];
						if(0<=xx && xx<w && 0<=yy && yy<h
						&& field[yy][xx]==1 && !visited[yy][xx]){
							qu.push(mp(yy,xx));
							visited[yy][xx]=true;
						}
					}
				}
				cnt++;
			}
		}

		printf("%d\n",cnt);
	}

	return 0;
}

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 < 0 || H <= nh || nw < 0 || W <= nw) {
                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];

        // 探索開始
        int count = 0;
        for (int h = 0; h < H; ++h) {
            for (int w = 0; w < W; ++w) {
                if (field[h][w] == 0) continue; // 残島じゃなかったらスルー
                dfs(h, w);
                ++count;
            }
        }
        cout << count << endl;
    }
}

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

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

int main() {
    int Map[100][100];
    while(true)
    {
        int w, h;
        cin >> w >> h;
        if(w == 0 && h == 0) break;

        for(int i = 0; i < h; ++i) {
            for(int j = 0; j < w; ++j) {
                cin >> Map[i][j];
            }
        }

        // 左上からラスタ走査
        int res = 0;
        for(int i = 0; i < h; ++i) {
            for(int j = 0; j < w; ++j) {
                if(Map[i][j] == 1) {
                    ++res;
                    queue<pair<int,int>> que;
                    que.push(make_pair(i,j));
                    Map[i][j] = 0;
                    while(!que.empty()){
                        int x = que.front().first;
                        int y = que.front().second;
                        que.pop();
                        for(int k = 0; k < 8; ++k) {
                            int nx = x + dx[k];
                            int ny = y + dy[k];
                            if(nx < 0 || nx >= h || ny < 0 || ny >= w) continue;
                            if(Map[nx][ny] == 1) {
                                que.push(make_pair(nx, ny));
                                Map[nx][ny] = 0;
                            }
                        }
                    }
                    
                }
            }
        }
        cout << res << endl;
    }
    return 0;
}