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;
template <class T>
bool chmax(T& a, const T& b)
{
    if (a < b) {
        a = b;
        return 1;
    }
    return 0;
}
template <class T>
bool chmin(T& a, const T& b)
{
    if (b < a) {
        a = b;
        return 1;
    }
    return 0;
}

#define rep(i, n) for (int i = 0; i < (int)n; i++)
#define all(x) (x).begin(), (x).end() //sortなどの引数を省略したい
#define F first
#define S second

typedef long long ll;
const ll MOD = 1e9 + 7;
const int inf = 1000000;
const int minf = -1000000;
const ll lnf = 1e12;
const ll mlnf = -1e12;

int H, W;
int dx[8] = { 0, 1, 0, -1, 1, 1, -1, -1 };
int dy[8] = { 1, 0, -1, 0, 1, -1, 1, -1 };
void dfs(vector<vector<int>>& field, int x, int y);
int main()
{
    while (1) {
        cin >> W >> H;
        if (H == 0 && W == 0)
            break;
        vector<vector<int>> field(H, vector<int>(W));
        rep(i, H) rep(j, W) cin >> field[i][j];
        int ans = 0;
        for (int h = 0; h < H; h++) {
            for (int w = 0; w < W; w++) {
                if (field[h][w] == 0)
                    continue;
                dfs(field, h, w);
                ans++;
            }
        }
        cout << ans << endl;
    }
}

void dfs(vector<vector<int>>& field, int x, int y)
{
    field[x][y] = 0;
    for (int i = 0; i < 8; i++) {
        int nx = x + dx[i];
        int ny = y + dy[i];
        if (nx < 0 || H <= nx || ny < 0 || W <= ny)
            continue;
        if (field[nx][ny] == 0)
            continue;
        dfs(field, nx, ny);
    }
}

C++: #include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
int map[60][60];
int main(void) {
	vector<int> list;
	for (;;) {
		int w, h;
		cin >> w >> h;
		if (!(w&&h))return 0;
		int cnt = 1;
		for (int i = 0; i < h; i++) {
			for (int j = 0; j < w; j++) {
				int buf;
				cin >> buf;
				map[i][j] = (buf?cnt++:0);
			}
		}
		bool update = true;
		for (;update;){
			cnt = 0;
			update = false;
			for (int i = 0; i < h; i++) {
				for (int j = 0; j < w; j++) {
					if (!map[i][j])continue;
					for (int n = max(0, i - 1); n <= min(h-1, i + 1); n++) {
						for (int m = max(0, j - 1); m <= min(w-1, j + 1); m++) {
							if (!map[n][m])continue;
							if (map[i][j]>map[n][m]) {
								map[i][j] = map[n][m];
								update = true;
							}
						}
					}
				}
			}
		}
		vector<int> num;
		for (int i = 0; i < h; i++) {
			for (int j = 0; j < w; j++) {
				num.push_back(map[i][j]);
			}
		}
		sort(num.begin(), num.end());
		num.erase(unique(num.begin(),num.end()),num.end());
		cout << num.size()-((num[0]==0)?1:0)<<endl;
	}
	return 0;
}

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

struct Map {
	std::vector<bool> data; // true ????????¶
	int width;
	int height;

	void initialize(int width, int height) {
		this->width = width;
		this->height = height;
		data.resize(width * height);
	}

	bool is_ground(int x, int y) {
		return data[y * width + x];
	}

	void set_as_sea(int x, int y) {
		data[y * width + x] = false;
	}
};

void paint(Map& map, int x, int y) {
	if (x < 0 || x >= map.width || y < 0 || y >= map.height) return;
	if (!map.is_ground(x, y)) return;

	map.set_as_sea(x, y);

	paint(map, x - 1, y - 1);
	paint(map, x - 1, y);
	paint(map, x - 1, y + 1);
	paint(map, x, y - 1);
	paint(map, x, y + 1);
	paint(map, x + 1, y - 1);
	paint(map, x + 1, y);
	paint(map, x + 1, y + 1);
}

int main()
{
	Map map;

	while (true) {
		int w, h;
		std::cin >> w >> h;

		if (w == 0) return 0;

		map.initialize(w, h);

		for (int i = 0; i < w * h; i++) {
			int c;
			std::cin >> c;
			map.data[i] = c == 1;
		}

		int count = 0;

		for (int y = 0; y < h; y++) {
			for (int x = 0; x < w; x++) {
				if (map.is_ground(x, y)) {
					count++;
					paint(map, x, y);
				}
			}
		}

		std::cout << count << std::endl;
	}
}

C++: #include <bits/stdc++.h>
#define chmin(a, b) ((a)=min((a), (b)))
#define chmax(a, b) ((a)=max((a), (b)))
#define fs first
#define sc second
#define eb emplace_back
using namespace std;
 
typedef long long ll;
typedef pair<int, int> P;
typedef tuple<int, int, int> T;
 
const ll MOD=1e9+7;
const ll INF=1e18;
 
int dx[]={1, -1, 0, 0};
int dy[]={0, 0, 1, -1};

int mp[55][55];
int check[55][55];

int dx2[] = {-1,0,1,1,1,0,-1,-1};
int dy2[] = {1,1,1,0,-1,-1,-1,0};

int main(){

    while(true){
        int w,h;
        int ans = 0;
        cin >> w >> h;
        if(w + h == 0) break;
        for(int i = 0;i < h;i++){
            for(int j = 0;j < w;j++){
                cin >> mp[i][j];
                check[i][j] = 0;
            }
        }
        for(int i = 0;i < h;i++){
            for(int j = 0;j < w;j++){
                if(mp[i][j] == 1 && check[i][j] == 0){
                    ans++;
                    queue<P> que;
                    que.push(P(i,j));
                    while(!que.empty()){
                        P q = que.front(); que.pop();
                        if(check[q.fs][q.sc] != 0) continue;
                        check[q.fs][q.sc] = 1;
                        for(int k = 0;k < 8;k++){
                            int ni = q.fs + dx2[k];
                            int nj = q.sc + dy2[k];
                            if(min(ni,nj) >= 0 && ni < h && nj < w && mp[ni][nj] == 1 && check[ni][nj] == 0){
                                que.push(P(ni,nj));
                            }
                        }
                    }
                }
            }
        }
        cout << ans << endl;
    }

}