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

void dfs(int x, int y)
{
    m[x][y] = 0;
    for (int i = 0; i < 8; i++) {
        int nx = x + dx[i];
        int ny = y + dy[i];
        
        if (nx < 0 || ny < 0 || nx >= w || ny >= h)
            continue;
        else if (m[nx][ny] == 1)
            dfs(nx, ny);
    }
}

int main()
{
    while (cin >> w >> h, w || h) {
        isl = 0;

        for (int i = 0; i < h; i++)
            for (int j = 0; j < w; j++)
                cin >> m[i][j];

        for (int i = 0; i < h; i++) 
            for (int j = 0; j < w; j++)
                if (m[i][j] == 1) {
                    isl++;
                    dfs(i, j);
                }
            
        cout << isl << endl;
    }

    return 0;
}

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

int myMap[50][50];
int w, h;
int ans;

bool safe(int x, int y){
    return (0 <= x && 0 <= y) && (x < w && y < h);
}

void del(int x, int y){
    myMap[x][y] = 0;
    if (safe(x+1, y) && myMap[x+1][y]) del(x+1, y);
    if (safe(x+1, y+1) && myMap[x+1][y+1]) del(x+1, y+1);
    if (safe(x+1, y-1) && myMap[x+1][y-1]) del(x+1, y-1);
    if (safe(x, y+1) && myMap[x][y+1]) del(x, y+1);
    if (safe(x, y-1) && myMap[x][y-1]) del(x, y-1);
    if (safe(x-1, y-1) && myMap[x-1][y-1]) del(x-1, y-1);
    if (safe(x-1, y+1) && myMap[x-1][y+1]) del(x-1, y+1);
    if (safe(x-1, y) && myMap[x-1][y]) del(x-1, y);
    return;
}

int main(){

    while (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 >> myMap[i][j];
	    }
	}

	ans = 0;	
	for (int i = 0; i < w; i++){
	    for (int j = 0; j < h; j++){
		if (myMap[i][j] == 1){
		    ans++;
		    del(i, j);
		}
	    }
	}

	cout << ans << endl;
    }
    
}

C++: #define _CRT_SECURE_NO_WARNINGS

#include <iostream>
#include <string>
#include <vector>
#include <cmath>
#include <fstream>
#include <set>
#include <utility>
#include <algorithm>
#include <queue>
#include <stack>
#include <deque>
#include <numeric>
#include <sstream>
#include <list>
#include <map>
#include <functional>
#include <iterator>

#define rep(i,p,n) for(int i=(int)p;i<(int)n;i++)
#define repp(i,p,n) for(int i=(int)p;i>=(int)n;i--)
#define Sort(x) sort(x.begin(),x.end())
#define PSort(x) sort(begin(x), end(x), pairCompare)
#define ll long long
#define INF 2000000000
#define pb push_back
#define mp make_pair
#define PI 3.14159265358979
int dx[4] = { -1,0,1,0 }, dy[4] = { 0,1,0,-1 };
using namespace std;

vector<vector<int>> v;
int w, h;

void dfs(int y, int x) {
	if (v[y][x] == 1)v[y][x] = 0;

	for (int i = -1; i <= 1; i++) {
		for (int j = -1; j <= 1; j++) {
			int nx = x + i, ny = y + j;

			if (!(nx < 0 || ny < 0 || nx >= w||ny >= h)&&v[ny][nx] == 1) dfs(ny, nx);
		}
	}
	
	return;
}

int main(){
	while (1) {
		int ans=0;
		cin >> w >> h;
		if (w == 0 && h == 0)break;
		v.resize(h, vector<int>(w));
		rep(i, 0, h) {
			rep(j, 0, w) {
				cin >> v[i][j];
			}
		}

		rep(i, 0, h) {
			rep(j, 0, w) {
				if (v[i][j] == 1) {
					ans++;
					dfs(i, j);
				}
			}
		}
		cout << ans << endl;
	}
	
	return 0;
}

C++: #include<cstdio>
using namespace std;
void func(int,int);
int a,b;
int sima[51][51];
int cnt;
int y,x;
int main(void)
{
	int i,j;
	scanf("%d",&a);
	scanf("%d",&b);
	while(!(a==0 && b==0)){
		
		for(i=0;i<b;i++){
			for(j=0;j<a;j++){
				scanf("%d",&sima[i][j]);
			}
		}
		cnt=0;
		for(i=0;i<b;i++){
			for(j=0;j<a;j++){
				if(sima[i][j]==1){
					func(i,j);
					cnt++;
					//printf("%d\n",cnt);
				}
			}
		}
		printf("%d\n",cnt);
		scanf("%d",&a);
		scanf("%d",&b);
	}
	return 0;
}
void func(int y,int x)
{
	if(y-1>=0){
		if(sima[y-1][x]==1){
			sima[y-1][x]=0;
			func(y-1,x);
		}
	}
	if(x-1>=0){
		if(sima[y][x-1]==1){
			sima[y][x-1]=0;
			func(y,x-1);	
		}
	}
	if(y+1<=a){
		if(sima[y+1][x]==1){
			//printf("%d\n",sima[y+1][x]);
			sima[y+1][x]=0;
			func(y+1,x);
		}
	}
	if(x+1<=b){
		if(sima[y][x+1]==1){
			sima[y][x+1]=0;
			func(y,x+1);
		}
	}
	if(y-1>=0 && x+1<=b){
		if(sima[y-1][x+1]==1){
			sima[y-1][x+1]=0;
			func(y-1,x+1);
		}
	}
	if(y-1>=0 && x-1>=0){
		if(sima[y-1][x-1]==1){
			sima[y-1][x-1]=0;
			func(y-1,x-1);
		}
	}
	if(y+1<=a && x+1<=b){
		if(sima[y+1][x+1]==1){
			sima[y+1][x+1]=0;
			func(y+1,x+1);
		}
	}
	if(y+1<=a && x-1>=0){
		if(sima[y+1][x-1]==1){
			sima[y+1][x-1]=0;
			func(y+1,x-1);
		}
	}
}

C++: #include <bits/stdc++.h>
#define debug(x) cerr << #x << ": " << x << '\n';
using namespace std;
using ll = long long;
using P = pair<int, int>;
const int INF = (int)1e9;
const int MOD = (int)1e9 + 7;

int dx[8] = {0, 1, 0, -1, 1, 1, -1, -1};
int dy[8] = {1, 0, -1, 0, 1, -1, 1, -1};
char c[50][50];

void dfs(int y, int x, int h, int w){
    c[y][x] = '0';
    for(int i = 0; i < 8; i++){
        int ny = y + dy[i], nx = x + dx[i];
        if(ny < 0 or h <= ny or nx < 0 or w <= nx or c[ny][nx] == '0') continue;
        dfs(ny, nx, h, w);
    }
}

int main(void){
    while(true){
        int w, h;
        cin >> w >> h;
        if(w == 0 and h == 0) break;

        for(int y = 0; y < h; y++){
            for(int x = 0; x < w; x++){
                cin >> c[y][x];
            }
        }

        int res = 0;
        for(int y = 0; y < h; y++){
            for(int x = 0; x < w; x++){
                if(c[y][x] == '0') continue;

                dfs(y, x, h, w);
                res++;
            }
        }

        cout << res << '\n';
    }

    return 0;
}