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 CountIsland(int w,int h,int c[][50]);
void CheckIsland(int w,int h,int c[][50]);
void debugg(int w,int h,int c[][50]);
int main(){
	int w,h;
	int c[50][50];
	while(true){
		for(int i=0;i<50;i++){
			for(int j=0;j<50;j++){
				c[i][j]=-1;
			}
		}
		cin >> w >> h;
		if(w==0&&h==0){break;}
		for(int i=0;i<h;i++){
			for(int j=0;j<w;j++){
				cin >> c[i][j];
			}
		}
		cout << CountIsland(w,h,c) << endl;
	}
	return 0;
}
int CountIsland(int w,int h,int c[][50]){
	int r=0;
	for(int i=0;i<h;i++){
		for(int j=0;j<w;j++){
			if(c[i][j]==1){
				r++;
				CheckIsland(j,i,c);
			}
		}
	}
	return r;
}
void debugg(int w,int h,int c[][50]){
	cout << endl;
	for(int i=0;i<h;i++){
		for(int j=0;j<w;j++){
			cout << c[i][j] << " ";
		}
		cout << endl;
	}
}
void CheckIsland(int w,int h,int c[][50]){
	c[h][w] = 0;
	for(int i=-1;i<=1;i++){
		for(int j=-1;j<=1;j++){
			if(i == -1 && h == 0 || j == -1 && w == 0 || i == 1 && h == 49 || j == 1 && w == 49||i == 0 && j == 0){continue;}
			if(c[i+h][j+w]==1){
				CheckIsland(j+w,i+h,c);
			}
		}
	}
}

C++: #include<iostream>
#define N 51
using namespace std;

int w, h, ans = 0, map[N][N];

void search_zahyou(int w, int h);

int main(){
	while(cin >>w >>h){
		ans = 0;
		if(w == 0 && h == 0) break;
		for(int i = 0; i < h; i++){
			for(int k = 0; k < w; k++){
				cin >>map[i][k];
			}
		}
		for(int i = 0; i < h; i++){
			for(int k = 0; k < w; k++){
				if(map[i][k] == 0){
					continue;
				}
				else{
					ans++;
					search_zahyou(i, k);
				}
			}
		}
		cout <<ans <<endl;
	}
	return 0;
}

void search_zahyou(int inh, int inw){
	int searchh[8] = {-1, -1, -1, 0, 1, 1, 1, 0}, searchw[8] = {-1, 0, 1, 1, 1, 0, -1, -1};
	if(h <= inh || w <= inw || inh < 0 || inw < 0){
	} else{
		map[inh][inw] = 0;
		for(int i = 0; i < 8; i++){
			if(map[inh + searchh[i]][inw + searchw[i]] == 1){
				search_zahyou(inh + searchh[i], inw + searchw[i]);
			}
		}
	}
}

C++: #include <iostream>

using namespace std;

int w,h;
int dx[8] = { -1 , -1 , -1 ,  0 , 0 ,  1 , 1 , 1};
int dy[8] = { -1 ,  0 ,  1 , -1 , 1 , -1 , 0 , 1};
int map[51][51];

void check(int x , int y){
	int mx,my;

	for(int i=0 ; i<8 ; i++){//üÍWûüð²×é
		mx = x + dx[i];
		my = y + dy[i];

		//tB[hOÉoÄ¢È¯êÎ²×é(0ÈãE³Èà)
		if(mx>=0 && mx<w && my>=0 && my<h){
			if(map[my][mx]==1){//¾Á½ç
				map[my][mx] = 2;//ñdÉ²×È¢½ßÉÊÌlðüêé
				check( mx , my );
			}
		}
	}
}

int main(){
	int count;//ÌðJEg·éÏ

	while(1){
		//ÏÌú»
		count = 0;
		
		//E³ÌüÍ
		cin >> w >> h;
		if(w==0 && h==0) break;//0 0ªüÍ³ê½çI¹

		//tB[hª©C©ÌîñðüÍ
		for(int y=0 ; y<h ; y++){
			for(int x=0 ; x<w ; x++){
				cin >> map[y][x];
			}
		}

		for(int y=0 ; y<h ; y++){
			for(int x=0 ; x<w ; x++){
				if(map[y][x]==1){//¾Á½çÄAÖðÄÑo·
					map[y][x] = 2;
					count++;
					check( x , y );
				}
			}
		}

		//¦ÌoÍ
		cout << count << endl;
	}

	return 0;
}

C++: #include <iostream>
#include <queue>
#include <cstdio>
#include <cstring>
#define rep(i,n) for(int i=0;i<(n);i++)

using namespace std;

typedef pair<int, int> P;
const int dir[][2] = { {-1, 0 }, { -1, 1 }, { 0, 1 }, { 1, 1 }, { 1, 0 }, { 1, -1 }, {0, -1 }, {-1, -1 } };
int w, h;
int Map[52][52];
bool used[52][52];

void bfs (int row, int col )
{
	queue<P> que;
	que.push (P (row, col ) );
	while (!que.empty() ){
		P curr = que.front(); que.pop();
		int cr = curr.first, cc = curr.second;
		used[cr][cc] = true;
		rep (k, 8 ){
			int nr = cr + dir[k][0];
			int nc = cc + dir[k][1];
			if (nr < 0 || nc < 0 || nr >= h || nc >= w || Map[nr][nc] == 0 || used[nr][nc] ) continue;
			que.push (P (nr, nc ) );
		} // end rep
	} // end while
}

int main()
{
	while (scanf ("%d %d", &w, &h ) && w && h ){
		memset (used, false, sizeof (used ) );
		rep (i, h ){
			rep (j, w ){
				scanf (" %d", Map[i]+j );
			} // end rep
		} // end rep
		int cnt = 0;
		rep (i, h ){
			rep (j, w ){
				if (Map[i][j] == 1 && !used[i][j] ){
					bfs (i, j );
					cnt++;
				} // end if
			} // end rep
		} // end rep
		printf ("%d\n", cnt );
	} // end loop
		
	return 0;
}