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>

using namespace std;
int w, h;
int c[50][50];
int dx[]={0, 0, 1, 1, 1, -1, -1, -1};
int dy[]={1, -1, 0, 1, -1, 0, 1, -1};
int used[50][50];

void rec(int i, int j){
   used[i][j]=1;
   for(int k=0; k<8; k++){
      int ni=i+dy[k];
      int nj=j+dx[k];
      if(!(0<=ni&&ni<h&&0<=nj&&nj<w)) continue;
      if(c[ni][nj]&&!used[ni][nj]) rec(ni, nj);
   }
}

int main(){

   while(1){
      cin>> w>> h;
      if(!(w||h)) break;
      for(int i=0; i<h; i++){
         for(int j=0; j<w; j++){
            cin>> c[i][j];
         }
      }

      fill((int*)used, (int*)used+50*50, 0);
      int cnt=0;
      for(int i=0; i<h; i++){
         for(int j=0; j<w; j++){
            if(c[i][j]&&!used[i][j]){
               cnt++;
               rec(i, j);
            }
         }
      }

      cout<< cnt<< endl;
   }

   return 0;
}

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

using std::cin;
using std::cout;
using std::endl;

int main(void) {
	int w,h;
	cin >> w;
	cin >> h;

	while (w!=0||h!=0) {
		int count = 0;
		std::stack<int> st_x;
		std::stack<int> st_y;
		int xn,yn;
		int c;
		bool all = false;
		std::vector< std::vector<bool> > island(h+2, std::vector<bool>(w+2));
		for (int i = 0; i < h+2; i++) {
			for (int j = 0; j < w+2; j++) {
				if (i==0||i==h+1||j==0||j==w+1) {
					island[i][j] = false;
				} else {
					cin >> c;
					if (c==1) {
						island[i][j] = true;
						st_x.push(j);
						st_y.push(i);
					} else {
						island[i][j] = false;
					}
				}
			}
		}

		while (!st_x.empty()) {
			xn = st_x.top();
			yn = st_y.top();
			st_x.pop();
			st_y.pop();
			if (island[xn][yn]) {
				std::stack<int> st_xn,st_yn;
				island[xn][yn] = false;
				count++;
				st_xn.push(xn);
				st_yn.push(yn);
				while (!st_xn.empty()) {
					xn = st_xn.top();
					yn = st_yn.top();
					st_xn.pop();
					st_yn.pop();
					if (island[xn+1][yn]) {
						st_xn.push(xn+1);
						st_yn.push(yn);
						island[xn+1][yn] = false;
					}
					if (island[xn-1][yn]) {
						st_xn.push(xn-1);
						st_yn.push(yn);
						island[xn-1][yn] = false;
					}
					if (island[xn+1][yn+1]) {
						st_xn.push(xn+1);
						st_yn.push(yn+1);
						island[xn+1][yn+1] = false;
					}
					if (island[xn+1][yn-1]) {
						st_xn.push(xn+1);
						st_yn.push(yn-1);
						island[xn+1][yn-1] = false;
					}
					if (island[xn-1][yn+1]) {
						st_xn.push(xn-1);
						st_yn.push(yn+1);
						island[xn-1][yn+1] = false;
					}
					if (island[xn-1][yn-1]) {
						st_xn.push(xn-1);
						st_yn.push(yn-1);
						island[xn-1][yn-1] = false;
					}
					if (island[xn][yn+1]) {
						st_xn.push(xn);
						st_yn.push(yn+1);
						island[xn][yn+1] = false;
					}
					if (island[xn][yn-1]) {
						st_xn.push(xn);
						st_yn.push(yn-1);
						island[xn][yn-1] = false;
					}
				}
			}
		}
		cout << count << endl;

		cin >> w;
		cin >> h;
	}
		return 0;
}

C++: 
#include <cstdio>
#include <iostream>
#include <algorithm>
#include <cstdlib>
#include <cmath>
#include <vector>
#include <ctime>
#include <string>
#include <map>
#include <stack>
#include <queue>

using namespace std;

int w, h;
const int MAX = 50;
int c[MAX][MAX];


void check(int x, int y){
	c[x][y] = 0;
    for(int dx = -1; dx <= 1; dx++){
        for(int dy = -1; dy <= 1; dy++){
            if(x + dx >= 0 && x + dx <= w  && y + dy >= 0 && y + dy <= h && c[x + dx][y + dy] == 1){
            	check(x + dx, y + dy);
            } 
        }
    }
	
}

int main(void){

	for(int i = 0; i < MAX ; i++){
		for(int j = 0; j < MAX; j++){
			c[i][j] = 0;
		}
	}

	cin >> w >> h;
	while(w != 0 && h != 0){
		int ans = 0;
		for(int i = 0; i < h ; i++){
			for(int j = 0; j < w; j++){
				cin >> c[i][j];
			}
		}

		for(int i = 0; i < h ; i++){
			for(int j = 0; j < w; j++){
				if(c[i][j] == 1){
					check(i, j);
					ans++;
				}
			}
		}
		cout << ans << endl;

		cin >> w >> h;
	}
	
    return 0;
}