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<algorithm>
#include<vector>
#include<numeric>
#include<string>
#include<cmath>
#include<set>
#include<queue>
#include<bitset>
using namespace std;
const int inf = 1001001000;

void dfs(vector<vector<int>> &graph, int v, set<int> &seen){
	seen.insert(v);
	for (int i=0;i<graph[v].size();i++){
		int nxt = graph[v][i];
		if (seen.count(nxt)) continue;
		dfs(graph, nxt, seen);
	}
}

void print(vector<vector<int>> a){
	for (int i=0;i<a.size(); i++){
		if (a[i].size() == 0) continue;
		for (int j=0;j<a[i].size();j++){
			cout << a[i][j] << " ";
		}
		cout << endl;
	}
}

int main(){
	while(true){
		int w,h; cin >> w >> h;
		if (w == 0 && h == 0) break;
		vector<vector<int>> map(h+2,vector<int>(w+2,0));
		for (int i=1;i<h+1;i++){
			for (int j=1;j<w+1;j++){
				int c; cin >> c;
				map[i][j] = c;
			}
		}
		vector<vector<int>> graph;
		int r = h+2,c=w+2;
		for (int i = 0; i < r; i++){
			for (int j = 0; j < c;j++){
				vector<int> a;
				if (map[i][j] == 1){	
					for (int k = -1; k < 2; k++){
						for (int l = -1; l < 2; l++){
							if (map[i+k][j+l] == 1) a.push_back((i+k)*c+j+l);
						}
					}
					
				}
				graph.push_back(a);
			}
		}
		set<int> gseen;
		int ans = 0;
		for (int i = 0; i < graph.size(); i++){
			set<int> seen;
			if (graph[i].size() == 0) continue;
			if (gseen.find(i) == gseen.end()){
				dfs(graph,i,seen);
				ans++;
				set_union(seen.begin(),seen.end(),gseen.begin(),gseen.end(),inserter(gseen,gseen.end()));
			}
			
		}
		cout << ans << endl;
	}
	
	return 0;
}

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

#define INF INT_MAX
#define ll long long

using namespace std;

int main(){
	while(true){
		int w,h;
		cin >> w >> h;
		if(w == 0 && h == 0)
			break;
		int c[h][w];
		//??\???
		for(int j = 0;j < h;j++){
			for(int i = 0;i < w;i++){
				cin >> c[j][i];
			}
		}

		//??????????????°????????????
		int ans = 0;
		for(int j = 0;j < h;j++){
			for(int i = 0;i < w;i++){
				if(c[j][i] == 1){
					ans++;
					vector< pair<int,int> > v;
					v.push_back(make_pair(j,i));
					while(!v.empty()){
						int y = v.back().first, x = v.back().second;
						c[y][x] = 0;	//????????¶????????????
						v.pop_back();
						for(int dirY = -1;dirY < 2;dirY++){
							for(int dirX = -1;dirX < 2;dirX++){
								int yy = y + dirY,xx = x + dirX;
								if((0 <= yy && yy < h) && (0 <= xx && xx < w) && (c[yy][xx] == 1)){
									v.push_back(make_pair(yy,xx));
								}
							}
						}
					}
				}
			}
		}
		cout << ans << endl;
	}
	return 0;
}

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

typedef pair<int,int> pii;
typedef vector<int> vi;
typedef vector<vi> vvi;

constexpr int dx[8]={1,1,1,0,0,-1,-1,-1};
constexpr int dy[8]={1,0,-1,1,-1,1,0,-1};

vvi t;
int W,H;

void dfs(int x,int y){
    t[x][y]='0';
    for(int i=0;i<8;i++){
        int nx = x + dx[i];
        int ny = y + dy[i];
        if(nx>=0 && nx<H && ny>=0 && ny<W && t[nx][ny]==1) dfs(nx,ny);
    }
    return;
}

int main(){
    while(cin>>W>>H){
        if(W==0&&H==0) return 0;

        t.resize(H);
        for(int i=0;i<H;i++) t[i].resize(W);

        for(int i=0;i<H;i++) for(int j=0;j<W;j++) cin>>t[i][j];

        int cnt=0;

        for(int i=0;i<H;i++) for(int j=0;j<W;j++) if(t[i][j]==1){
            cnt++;
            dfs(i,j);
        }
        cout << cnt << endl;
    }
}

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

const int dx[] = {1, 0, -1, 0, 1, 1, -1, -1}, dy[] = {0, 1, 0, -1, 1, -1, 1, -1};
int field[51][51];
int h, w;

void sol(int x, int y)
{
  field[x][y] = 0;
  for (int i = 0; i < 8; i++){
    if ((0 <= x + dx[i] && x + dx[i] < h) || (0 <= y + dy[i] && y + dy[i] < w))
    if (field[x + dx[i]][y + dy[i]] == 1) sol(x + dx[i], y + dy[i]);
  }
}

int main()
{

  while (cin >> h >> w, h || w){
    int res = 0;
    for (int i = 0; i < h; i++){
      for (int j = 0; j < w; j++){
        cin >> field[i][j];
      }
    }

    for (int i = 0; i < h; i++){
      for (int j = 0; j < w; j++){
        if (field[i][j] == 1){
          res++;
          sol(i, j);
        }
      }
    }
    cout << res << endl;
  }
}