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;

/*bool check(const int x, const int y, const int LandNum, const int aNodeCol[50][50], const int aXMax, const int aYMax){
	if ((x<0 || x >= aXMax) || (y<0 || y >= aYMax) || (aNodeCol[x][y] != 1)){
		return false;
	}
	return true;
}*/

bool LandConfirmedAndMawariCheck(const int x, const int y, const int LandNum, int aNodeCol[50][50], const int aXMax, const int aYMax){
	if (aNodeCol[x][y] == 1){
		aNodeCol[x][y] = LandNum;
		/*if (check(x - 1, y, LandNum, aNodeCol, aXMax, aYMax))LandConfirmedAndMawariCheck(x - 1, y, LandNum, aNodeCol, aXMax, aYMax);
		if (check(x - 1, y - 1, LandNum, aNodeCol, aXMax, aYMax))LandConfirmedAndMawariCheck(x - 1, y - 1, LandNum, aNodeCol, aXMax, aYMax);
		if (check(x - 1, y + 1, LandNum, aNodeCol, aXMax, aYMax))LandConfirmedAndMawariCheck(x - 1, y + 1, LandNum, aNodeCol, aXMax, aYMax);
		if (check(x + 1, y - 1, LandNum, aNodeCol, aXMax, aYMax))LandConfirmedAndMawariCheck(x + 1, y - 1, LandNum, aNodeCol, aXMax, aYMax);
		if (check(x + 1, y, LandNum, aNodeCol, aXMax, aYMax))LandConfirmedAndMawariCheck(x + 1, y, LandNum, aNodeCol, aXMax, aYMax);
		if (check(x + 1, y + 1, LandNum, aNodeCol, aXMax, aYMax))LandConfirmedAndMawariCheck(x + 1, y + 1, LandNum, aNodeCol, aXMax, aYMax);
		if (check(x, y - 1, LandNum, aNodeCol, aXMax, aYMax))LandConfirmedAndMawariCheck(x, y - 1, LandNum, aNodeCol, aXMax, aYMax);
		if (check(x, y + 1, LandNum, aNodeCol, aXMax, aYMax))LandConfirmedAndMawariCheck(x, y + 1, LandNum, aNodeCol, aXMax, aYMax);*/
		if (!((x - 1<0 || x - 1 >= aXMax) || (y    <0 || y     >= aYMax) || (aNodeCol[x-1][y    ] != 1)))LandConfirmedAndMawariCheck(x - 1, y    , LandNum, aNodeCol, aXMax, aYMax);
		if (!((x - 1<0 || x - 1 >= aXMax) || (y - 1<0 || y - 1 >= aYMax) || (aNodeCol[x-1][y - 1] != 1)))LandConfirmedAndMawariCheck(x - 1, y - 1, LandNum, aNodeCol, aXMax, aYMax);
		if (!((x - 1 < 0 || x - 1 >= aXMax) || (y + 1 < 0 || y + 1 >= aYMax) || (aNodeCol[x - 1][y + 1] != 1))){
			LandConfirmedAndMawariCheck(x - 1, y + 1, LandNum, aNodeCol, aXMax, aYMax);
		}
		if (!((x + 1<0 || x + 1 >= aXMax) || (y - 1<0 || y - 1 >= aYMax) || (aNodeCol[x+1][y - 1] != 1)))LandConfirmedAndMawariCheck(x + 1, y - 1, LandNum, aNodeCol, aXMax, aYMax);
		if (!((x + 1<0 || x + 1 >= aXMax) || (y    <0 || y     >= aYMax) || (aNodeCol[x+1][y    ] != 1)))LandConfirmedAndMawariCheck(x + 1, y    , LandNum, aNodeCol, aXMax, aYMax);
		if (!((x + 1<0 || x + 1 >= aXMax) || (y + 1<0 || y + 1 >= aYMax) || (aNodeCol[x+1][y + 1] != 1)))LandConfirmedAndMawariCheck(x + 1, y + 1, LandNum, aNodeCol, aXMax, aYMax);
		if (!((x    <0 || x     >= aXMax) || (y - 1<0 || y - 1 >= aYMax) || (aNodeCol[x  ][y - 1] != 1)))LandConfirmedAndMawariCheck(x    , y - 1, LandNum, aNodeCol, aXMax, aYMax);
		if (!((x    <0 || x     >= aXMax) || (y + 1<0 || y + 1 >= aYMax) || (aNodeCol[x  ][y + 1] != 1)))LandConfirmedAndMawariCheck(x    , y + 1, LandNum, aNodeCol, aXMax, aYMax);
		return true;
	}
	return false;
}



int main(void){
	int NodeCol[50][50];
	int a, b, c;
	int XMax, YMax;
	while(1){
		cin >> a >> b;
		if (a == 0&&b == 0)break;
		XMax = a; YMax = b;

		for (int Lone = 0;  Lone < YMax; ++Lone){
			for (int Ltwo = 0; Ltwo < XMax; ++Ltwo){
				cin >> c;
				NodeCol[Ltwo][Lone] = c;
			}
		}
		int t = 2;
		for (int Lone = 0;  Lone < XMax; ++Lone){
			for (int Ltwo= 0; Ltwo < YMax; ++Ltwo){
				if (NodeCol[Lone][Ltwo]==1)
				{
					if (LandConfirmedAndMawariCheck(Lone, Ltwo, t, NodeCol, XMax, YMax))t++;
				}
			}
		}
		cout << t-2<<endl;
	}
	return 0;
}

C++: #include <bits/stdc++.h>

using namespace std;

int w, h;
vector< vector<int> > c, island;

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

void dfs(int x, int y, int id) {

    island[y][x] = id;

    for(int i = 0; i < 8; i++) {

        int nx = x + dx[i];
        int ny = y + dy[i];

        if(nx < 0 || nx >= w || ny < 0 || ny >= h)
            continue;

        if(c[ny][nx] == 1 && island[ny][nx] != id)
            dfs(nx, ny, id);

    }

}

int main(){

    cin.tie(0);
    ios::sync_with_stdio(false);

    int ans;

    while(cin >> w >> h, w) {

        c.assign(h, vector<int>(w));
        island.assign(h, vector<int>(w, -1));
        ans = 0;

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

        for(int x = 0; x < w; x++)
            for(int y = 0; y < h; y++)
                if(c[y][x] == 1 && island[y][x] == -1)
                    dfs(x, y, ans++);

        cout << ans << endl;

    }

    return 0;

}

C++: #include<iostream>
#include<vector>
#include<algorithm>
#include<iomanip>
#include<stack>
#include<queue>
#include<string>
#include<set>
#include<map>
using namespace std;
#define rep(i,n) for(int i=0;(i)<(n);(i)++)
#define FOR(i,m,n) for(int i=(m);(i)<(n);(i)++)
typedef long long ll;
const int dx[8] = {0,1,1,1,0,-1,-1,-1};
const int dy[8] = {1,1,0,-1,-1,-1,0,1};
int w,h,res;

void dfs(int x,int y,int f,vector<vector<int> >& mp){
    if(mp[y][x]==1){
        if(f==0){
            f=1;
            res++;
        }
        mp[y][x]=0;
        rep(i,8){
            int nx=x+dx[i],ny=y+dy[i];
            if(nx>=0&&nx<w&&ny>=0&&ny<h){
                dfs(nx,ny,f,mp);
            }
        }
    }

}

int main(){
    while(cin >> w >> h,w|h){
        vector<vector<int> > c(h,vector<int>(w));
        
        rep(i,h)rep(j,w)cin >> c[i][j];
        res=0;
        rep(i,h)rep(j,w)dfs(j,i,0,c);
        cout << res << endl;
    }   
    return 0;
}