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>
#include <algorithm>
#include <cstring>

using namespace std;

namespace {
    const int MAX_W = 50;
    const int MAX_H = 50;
    int W, H;
    int F[MAX_H][MAX_W];
    bool input() {
        cin >> W >> H;
        if (W == 0 && H == 0) return false;
        for (int i = 0; i < H; i++) {
            for (int j = 0; j < W; j++) {
                cin >> F[i][j];
            }
        }
        return true;
    }

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

    void solve() {
        bool used[H][W];
        memset(used, 0, sizeof(used));
        int ans = 0;
        for (int i = 0; i < H; i++) {
            for (int j = 0; j < W; j++) {
                if (F[i][j] == 0) continue;
                if (used[i][j]) continue;
                typedef pair<int, int> P;
                queue<P> Q;
                Q.push(P(i, j));
                ans++;
                used[i][j] = true;
                while (!Q.empty()) {
                    P c = Q.front(); Q.pop();
                    int y = c.first, x = c.second;
                    for (int k = 0; k < 8; k++) {
                        int ny = y + dy[k];
                        int nx = x + dx[k];
                        if (ny < 0 || ny >= H) continue;
                        if (nx < 0 || nx >= W) continue;
                        if (F[ny][nx] == 0) continue;
                        if (used[ny][nx]) continue;
                        used[ny][nx] = true;
                        Q.push(P(ny, nx));
                    }
                }
            }
        }
        cout << ans << endl;
    }
}

int main() {
    while (input()) solve();
    return 0;
}

C++: #include <iostream>
#include <sstream>
#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <ctime>
#include <cstring>
#include <string>
#include <vector>
#include <stack>
#include <queue>
#include <deque>
#include <map>
#include <set>
#include <bitset>
#include <numeric>
#include <utility>
#include <iomanip>
#include <algorithm>
#include <functional>

using namespace std;
#define ll long long
#define REP(i,x) for(int i=0;i<(int)(x);i++)
#define REPS(i,x) for(int i=1;i<=(int)(x);i++)
#define RREP(i,x) for(int i=((int)(x)-1);i>=0;i--)
#define RREPS(i,x) for(int i=((int)(x));i>0;i--)
const ll mod = 1e9 + 7;


int w;
int h;
vector<vector<int> > c(50, vector<int>(50));
vector<vector<bool> > reached(50, vector<bool>(50,false));

void dfs(int y, int x){
    reached.at(y).at(x) = true;

    for(int dy = -1; dy <= 1; dy++){
        for(int dx = -1; dx <= 1; dx++){
            int nx = x + dx;
            int ny = y + dy;
			if(ny < 0 || h <= ny || nx < 0 || w <= nx || c.at(ny).at(nx) == 0) continue;          
            if(reached.at(ny).at(nx)) continue;
            dfs(ny,nx);

       }
    }
    
}




int main (){
while(cin>>w>>h,w!=0&&h!=0){
	
  	
    REP(i,h){//y
        REP(j,w){//x
          	reached.at(i).at(j) = false;
            cin >> c.at(i).at(j);
        }
    }
    int ans = 0;
    REP(i,h){
        REP(j,w){
            if(!reached.at(i).at(j) && c.at(i).at(j) == 1){
                dfs(i,j);
                ans++;
            }
            
        }
    }

    cout << ans << endl;




}

    return 0;
}

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

int c[100][100],ans;

int search(int x, int y){
	if(c[x][y] == 1){
		c[x][y] = 2;
		search(x-1, y-1);
		search(x-1, y);
		search(x-1, y+1);
		search(x, y-1);
		search(x, y+1);
		search(x+1, y-1);
		search(x+1, y);
		search(x+1, y+1);
	return 1;	
	}
	else return 0;
}

int main(){
	int w,h,i,j;
	while(cin >> w >> h && w > 0 && h >0){
		for(i = 1; i <= 99; i++){
			for(j = 1; j <= 99; j++){
				c[i][j] = 0;
			}
		}
		ans = 0;
		for(i = 1; i <= h; i++){
			for(j = 1; j <= w; j++){
				cin >> c[i][j];
			}
		}
		for(i = 1; i <= h; i++){
			for(j = 1; j <= w; j++){
				if(search(i, j) == 1){
					ans++;
				}
			}
		}
		cout << ans << endl;
	}
}

C++: #include <bits/stdc++.h>
#define REP(i,n) for(int i = 0 ; i < n ; ++i)

using namespace std;

#ifdef _DEBUG
#define debug_io fstream cin("input.txt");ofstream cout("output.txt");
#else
#define debug_io ;
#endif

int main()
{
	debug_io
	int w, h;
	while (cin >> w >> h, w + h) {
		int tile[55][55];
		REP(i, h) {
			REP(j, w) {
				cin >> tile[i][j];
			}
		}

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

		int ans = 0;
		REP(i, h) {
			REP(j, w) {
				if (tile[i][j] == 1) {
					vector<pair<int, int>> bfs;
					bfs.push_back({ i,j });

					while (bfs.size()) {
						auto now = bfs.front();
						bfs.erase(bfs.begin());
						int x = now.second;
						int y = now.first;
						if (tile[y][x] == 2) {
							continue;
						}
						tile[y][x] = 2;
						REP(k, 8) {
							int nx = max(0,min(x + dx[k],w-1));
							int ny = max(0, min(y + dy[k], h - 1));
							if (tile[ny][nx] == 1) {
								bfs.push_back({ ny,nx });
							}
						}
					}
					ans++;
					
				}
			}
		}
		cout << ans << endl;
	}
}