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<stdio.h>
#include<iostream>
#include<string>
using namespace std;

int main(){

	
	int w,h;
	while(1){
		cin>>w>>h;if(w==0&&h==0)break;
		int n[51][51]={};
	bool N[51][51]={};
		for(int i=0;i<h;i++)
			for(int j=0;j<w;j++)
			{int x;cin>>x;if(x==1)N[i][j]=true;}

		int c=0;
		for(int i=0;i<h;i++)
			for(int j=0;j<w;j++)
			{if(N[i][j]==true&&n[i][j]==0){
				c++;
				n[i][j]=c;
				if(n[i-1][j+1]==0)n[i-1][j+1]=c;
				if(n[i-1][j]==0)n[i-1][j]=c;
				if(n[i-1][j-1]==0)n[i-1][j-1]=c;
				if(n[i][j+1]==0)n[i][j+1]=c;
				if(n[i-1][j]==0)n[i-1][j]=c;
				if(n[i+1][j+1]==0)n[i+1][j+1]=c;
				if(n[i+1][j]==0)n[i+1][j]=c;
				if(n[i+1][j-1]==0)n[i+1][j-1]=c;
			}
			else if(N[i][j]==true&&n[i][j]>0){
				int y=n[i][j];
				n[i-1][j+1]=y;
				n[i-1][j]=y;
				n[i-1][j-1]=y;
				n[i][j+1]=y;
				n[i-1][j]=y;
				n[i+1][j+1]=y;
				n[i+1][j]=y;
				n[i+1][j-1]=y;
			}
			}

			for(int i=0;i<h;i++){
			for(int j=0;j<w;j++){
				int t=n[i][j];
				if(N[i][j]==true&&N[i][j+1]==true&&t>n[i][j+1])t=n[i][j+1];
				if(N[i][j]==true&&N[i][j-1]==true&&t>n[i][j-1])t=n[i][j-1];
				if(N[i][j]==true&&N[i+1][j+1]==true&&t>n[i+1][j+1])t=n[i+1][j+1];
				if(N[i][j]==true&&N[i+1][j]==true&&t>n[i+1][j])t=n[i+1][j];
				if(N[i][j]==true&&N[i+1][j-1]==true&&t>n[i+1][j-1])t=n[i+1][j-1];
				if(N[i][j]==true&&N[i-1][j+1]==true&&t>n[i-1][j+1])t=n[i-1][j+1];
				if(N[i][j]==true&&N[i-1][j]==true&&t>n[i-1][j])t=n[i-1][j];
				if(N[i][j]==true&&N[i-1][j-1]==true&&t>n[i-1][j-1])t=n[i-1][j-1];
				if(n[i][j]>t){
					for(int ii=0;ii<h;ii++)
			for(int jj=0;jj<w;jj++){
				if(n[i][j]==n[ii][jj])n[ii][jj]=t;
			}
				}
			}
			}

			int max=0;
			for(int i=0;i<h;i++){
			for(int j=0;j<w;j++){
				if(N[i][j]==true&&n[i][j]>max)max=n[i][j];
			}}
			cout<<max<<endl;
			}
return 0;
}

C++: #include <iostream>
#include <queue>
#include <stdio.h>

using namespace std;

#define NUM 50

int w, h;
int c[NUM][NUM];
bool visited[NUM][NUM];
queue<pair<int, int> > Q;

void init(){
    for(int i = 0; i < h; i++){
        for(int j = 0; j < w; j++){
            visited[i][j] = false;
        }
    }
}

bool can_visit(int i, int j){
    if(i < 0 || h <= i || j < 0 || w <= j){
        return false;
    }
    if(visited[i][j] || c[i][j] == 0){
        return false;
    }
    return true;
}

pair<int, int> find_new_place(){
    for(int i = 0; i < h; i++){
        for(int j = 0; j < w; j++){
            if(can_visit(i, j)){
                return make_pair(i, j);
            }
        }
    }

    return make_pair(-1, -1);
}

bool exec(void){
    scanf("%d %d", &w, &h);
    if(w == 0 && h == 0){
        return false;
    }

    init();

    for(int i = 0; i < h; i++){
        for(int j = 0; j < w; j++){
            scanf("%d", &c[i][j]);
        }
    }

    int count = 0;

    while(true){
        pair<int, int> new_place = find_new_place();
        if(new_place.first == -1){
            break;
        }

        count++;

        Q.push(new_place);
        visited[new_place.first][new_place.second] = true;
        while(!Q.empty()){
            pair<int, int> p = Q.front(); Q.pop();
            int x = p.first;
            int y = p.second;

            vector<pair<int, int> > v;
            v.push_back(make_pair(x, y + 1));
            v.push_back(make_pair(x, y - 1));
            v.push_back(make_pair(x + 1, y + 1));
            v.push_back(make_pair(x + 1, y));
            v.push_back(make_pair(x + 1, y - 1));
            v.push_back(make_pair(x - 1, y + 1));
            v.push_back(make_pair(x - 1, y));
            v.push_back(make_pair(x - 1, y - 1));

            for(auto&& item : v){
                int x_ = item.first;
                int y_ = item.second;
                if(can_visit(x_, y_)){
                    visited[x_][y_] = true;
                    Q.push(make_pair(x_, y_));
                }
            }
        }
    }

    printf("%d\n", count);

    return true;
}

int main(void){
    while(exec()){
        ;
    }
    
    return 0;
}

C++: #include <stdio.h>

	int sima[50][50];
	int cnt=0;
	int cflag=0;

int count_sima(int w,int h){
	if(w<0)return 0;
	if(h<0)return 0;
	if(sima[w][h]==3)return 0;
	if(sima[w][h]==0)return 0;

		if(cflag==0){
			cnt++;
			cflag=1;
		}
		

		sima[w][h]=0;

		count_sima(w,h+1);
		count_sima(w+1,h+1);
		count_sima(w+1,h);
		count_sima(w+1,h-1);
		count_sima(w,h-1);
		count_sima(w-1,h-1);
		count_sima(w-1,h);
		count_sima(w-1,h+1);


	return 0;
}


int main(void){
	int w2,h2; //島の大きさを格納する
	int p;

	scanf("%d %d",&w2,&h2);
	while(w2!=0 && h2!=0){

		//島配列をすべてを3にする
		for(int i=0; i<50; i++){
			for(int j=0; j<50; j++){
				sima[i][j]=3;
			}
		}

		//入力された地図のデータを設定
		for(int i=0; i<h2; i++){
			for(int j=0; j<w2; j++){
				scanf("%d",&p);
				sima[i][j]=p;
			}
		}

		//ここまで入力された地図のデータを設定

		for(int i=0; i<h2; i++){
			for(int j=0; j<w2; j++){
				count_sima(i,j);
				cflag=0;
			}
		}

		printf("%d\n",cnt);
		cnt=0;

		scanf("%d %d",&w2,&h2);
	}

	return 0;
}