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 <bits/stdc++.h>

using namespace std;

#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define all(v) v.begin(),v.end()
#define _GLIBCXX_DEBUG

using ll = long long;
using vi = vector<int>;
using vll = vector<ll>;
using vd = vector<double>;
using vvi = vector<vi>;
using vvll = vector<vll>;
using vvd = vector<vd>;
using vvvi = vector<vvi>;
using vvvll = vector<vvll>;
using vvvd = vector<vvd>;

const double pi=acos(-1);
const ll MOD=1e9+7;
const ll INF=(1LL<<60);

int w,h;
int graph[51][51];

void dfs(int x,int y,int x1,int y1){
    graph[x][y]=0;
    vi move={-1,0,1};
    for (int i:move){
        for (int j:move){
            if (i==0 && j==0)continue;
            else if (x+i<=0 || x+i>h || y+j<=0 || y+j>w)continue;
            else if (x+i==x1 && y+j==y1)continue;
            else if (graph[x+i][y+j]==0)continue;
            else dfs(x+i,y+j,x,y);
        }
    }
}

int main() {
    while (1){
        cin>>w>>h;
        if (w==0 && h==0)return 0;
        memset(graph,0,sizeof(graph));
        rep(i,h){
            rep(j,w){
                cin>>graph[i+1][j+1];
            }
        }
        int ans=0;
        for (int i=1;i<h+1;i++){
            for (int j=1;j<w+1;j++){
                if (graph[i][j]){
                    ans+=1;
                    dfs(i,j,0,0);
                }
            }
        }
        cout<<ans<<endl;
    }
    

    return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define rep(i,n) for(int i=0; i<(n); i++)
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return true; } return false; }
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return true; } return false; }

void dfs(int i, int j, vector<vector<int>> &map){
    if(map.at(i).at(j)==0) return;
    map.at(i).at(j)=0;
    vector<int> x={-1,0,1,-1,1,-1,0,1},y={-1,-1,-1,0,0,1,1,1};
    rep(k,8){
        dfs(i+x.at(k),j+y.at(k),map);
    }
}

int main(){
    while(true){
        int w,h; cin>>w>>h;
        int res=0;
        if(w==0 && h==0) break;
        vector<vector<int>> map(h+2,vector<int>(w+2,0));
        rep(i,h){
            rep(j,w){
                cin>>map.at(i+1).at(j+1);
            }
        }
        rep(i,h+2){
            rep(j,w+2){
                if(map.at(i).at(j)==1){
                    dfs(i,j,map);
                    res++;
                }
            }
        }
        cout<<res<<endl;
    }
}

C++: #include <bits/stdc++.h>
using namespace std;
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define rep(i,n) FOR(i,0,n)
#define repr(i,n) for(int i=(n)-1;0<=i;--i)
#define each(e,v) for(auto&& e:(v))
#define all(v) begin(v),end(v)
#define dump(x) cerr<<#x<<": "<<(x)<<endl
#define INF 100000000
#define IINF 9999999999999;
using vint = vector<int>;
using ll = long long;
using vll = vector<ll>;
template <class T> void chmin(T& a, const T& b) { a = min(a, b); }
template <class T> void chmax(T& a, const T& b) { a = max(a, b); }

bool earth[51][51];

void erase_island(int h, int w) {
    earth[h][w] = false;
    //cout << "# " << h << " " << w << endl;
    if(earth[h - 1][w - 1]) erase_island(h - 1, w - 1);
    if(earth[h - 1][w]) erase_island(h - 1, w);
    if(earth[h - 1][w + 1]) erase_island(h - 1, w + 1);
    if(earth[h][w + 1]) erase_island(h, w + 1);
    if(earth[h + 1][w + 1]) erase_island(h + 1, w + 1);
    if(earth[h + 1][w]) erase_island(h + 1, w);
    if(earth[h + 1][w - 1]) erase_island(h + 1, w - 1);
    if(earth[h][w - 1]) erase_island(h, w - 1);
}

int main() {
    //ofstream outputfile("output.txt");
    while(true) {
        int w, h;
        cin >> w >> h;
        if(w == 0 && h == 0) break;
        rep(i, h) rep(j, w) {
                int temp;
                cin >> temp;
                if(temp == 0) earth[i][j] = false;
                else earth[i][j] = true;
            }

        int ans = 0;
        rep(i, h) rep(j, w) {
                if(earth[i][j]) erase_island(i , j), ++ans;
            }

        cout << ans << endl;
    }

    return 0;
}

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

#define mod 1000000007

#define rep(i, n) for(int i=0; i<n; ++i)

using namespace std;
typedef long long ll;
const long long INF = 1LL << 60;

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

int W, H;
vector<vector<int> > c;
void dfs(int h, int w){
    c[h][w] = 0;
    rep(dir, 8){
        int nh = h + dx[dir];
        int nw = w + dy[dir];

        if(nh < 0 || nh >= H || nw < 0 || nw >= W || c[nh][nw] == 0)
            continue;
        dfs(nh, nw);
    }
}
 
int main(void){
    while(1){
        cin >> W >> H;
        if(W == 0 && H == 0)
            break;
        c.resize(H);
        rep(i, H){
            c[i].resize(W);
            rep(j, W)
                cin >> c[i][j];
        }
        int count = 0;
        rep(i, H){
            rep(j, W){
                if(c[i][j] == 0)
                    continue;
                dfs(i, j);
                count++;  
            }
        }
        cout << count << endl;
    }
	
	return 0;
}