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;
void kazoe(int p,int P, int box[50][50]){
  if(box[p][P+1]==1){
    box[p][P+1]=0;
    P=P+1;
    kazoe(p,P,box);
  }
  if(box[p+1][P+1]==1){
    box[p+1][P+1]=0;
    P=P+1;
    p=p+1;
 kazoe(p,P,box);
  }
  if(box[p+1][P]==1){
    box[p+1][P]=0;
    p=p+1;
 kazoe(p,P,box);
  }
  if(box[p+1][P-1]==1){
    box[p+1][P-1]=0;
    P=P-1;
    p=p+1;
 kazoe(p,P,box);
  }
  if(box[p][P-1]==1){
    box[p][P-1]=0;
    P=P-1;
 kazoe(p,P,box);
  }
  if(box[p-1][P-1]==1){
    box[p-1][P-1]=0;
    P=P-1;
    p=p-1;
 kazoe(p,P,box);
  }
  if(box[p-1][P]==1){
    box[p-1][P]=0;
    p=p-1;
 kazoe(p,P,box);
  }
  if(box[p-1][P+1]==1){
    box[p-1][P+1]=0;
    P=P+1;
    p=p-1;
 kazoe(p,P,box);
  }
}
int main(){
  int w,h,i,I,p,P,a=0;
  int box[50][50];
  while(1){
    cin>>w>>h;
    if(w==0&&h==0) break;
    for(i=0;i<h;i++){
      for(I=0;I<w;I++){
	cin>>box[i][I];
      }
    }
    for(i=0;i<h;i++){
      for(I=0;I<w;I++){
	if(box[i][I]==1){
	  p=i;
	  P=I;
	  box[p][P]=0;
	  kazoe(p,P,box);
	  box[i][I]=1;
	}
      }
    }
    for(i=0;i<h;i++){
      for(I=0;I<w;I++){
	if(box[i][I]==1) a++;
      }
    }
  
    cout<<a<<endl;
    a=0;
  }
  return 0;
}

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

int main(){
  bool map[52][52];
  int w,h;

  while(cin >> w >> h && w>0 && h>0){
    for(int i=0;i<52;i++){
      for(int j=0;j<52;j++)
        map[i][j]=false;
    }

    int land=0;

    for(int i=1;i<=h;i++){
      for(int j=1;j<=w;j++){
        int c;
        cin >> c;
        if(c==1){
          map[i][j]=true;
          land++;
        }
      }
    }

    int visited=0,cnt=0;
    queue<int> cur;
    int d[8]={-w-3,-w-2,-w-1,-1,1,w+1,w+2,w+3};

    while(visited<land){
      cnt++;
      for(int i=0;i<(w+2)*(h+2);i++){
        if(map[i/(w+2)][i%(w+2)]){
          map[i/(w+2)][i%(w+2)]=false;
          visited++;
          cur.push(i);
          break;
        }
      }
      while(!cur.empty()){
        for(int i=0;i<8;i++){
          if(map[(cur.front()+d[i])/(w+2)][(cur.front()+d[i])%(w+2)]){
            map[(cur.front()+d[i])/(w+2)][(cur.front()+d[i])%(w+2)]=false;
            visited++;
            cur.push(cur.front()+d[i]);
          }
        }
        cur.pop();
      }
    }

    cout << cnt << endl;
  }

  return 0;
}

C++: #include <iostream>
using namespace std;
int w, h, m[50][50], dx[8] = {-1, 0, 1, -1, 1, -1, 0, 1}, dy[8] = {-1, -1, -1, 0, 0, 1, 1, 1};
void dfs(int x, int y)
{
	int i, nx, ny;
	m[y][x] = 0;
	for (i = 0; i < 8; i++)
	{
		if (0 <= (nx = x+dx[i]) && nx <= w && 0 <= (ny = y+dy[i]) && ny <= h)
			if (m[ny][nx])
				dfs(nx, ny);
	}
}
int main()
{
	int n, i, j;
	while (cin >> w >> h)
	{
		if (w == 0 && h == 0) break;
		for (i = 0; i < h; i++)
			for (j = 0; j < w; j++)
				cin >> m[i][j];
		for (i = n = 0; i < h; i++)
			for (j = 0; j < w; j++)
				if (m[i][j])
					n++, dfs(j, i);
		cout << n << endl;
	}
}

C++: #include <bits/stdc++.h>
using namespace std;

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

void dfs(int x, int y) {
  land[x][y] = 2;
  int dx[8] = {1,1,1,0,0,-1,-1,-1};
  int dy[8] = {1,0,-1,1,-1,1,0,-1};
  for (int i = 0; i < 8; i++) {
    int nx = x + dx[i];
    int ny = y + dy[i];
    if (0 <= nx && nx < w && 0 <= ny && ny < h && land[nx][ny] == 1) dfs(nx, ny);
  }
  return;
}

int main() {
  bool jud = true;
  while (jud) {
  cin >> h >> w;
  if (h == 0 && w == 0) {
    jud == false;
    break;
  }
  if (jud == false) break;
  for (int a = 0; a < w; a++) {
    for (int b = 0; b < h; b++) {
      cin >> land[a][b];
    }
  }
  int ans = 0;
  for (int a = 0; a < w; a++) {
    for (int b = 0; b < h; b++) {
      if (land[a][b] == 1) {
        dfs(a, b);
        ans++;
      }
    }
  }
  cout << ans << endl;
  }
}

C++: #include<iostream>
#include<utility>
#include<queue>
#include<map>
#define h first
#define w second
using namespace std;
typedef pair<int, int> P;

const int MAX_H = 55;
const int MAX_W = 55;

int grid[MAX_H][MAX_W];
bool is_checked[MAX_H][MAX_W];

void solve(int W, int H) {
    map<P, bool> is_exist;
    for (int i = 0; i < H; i++) {
        for (int j = 0; j < W; j++) {
            cin >> grid[i][j];
            is_checked[i][j] = false;
            is_exist[P(i, j)] = true;
        }
    }
    queue<P> Q;
    int land_cnt = 0;
    for (int i = 0; i < H; i++) {
        for (int j = 0; j < W; j++) {
            if (grid[i][j] == 1 && !is_checked[i][j]) {
                Q.push(P(i, j));
                is_checked[i][j] = true;
                while (!Q.empty()) {
                    P now_pos = Q.front();
                    Q.pop();
                    for (int k = -1; k <= 1; k++) {
                        for (int l = -1; l <= 1; l++) {
                            P new_pos = P(now_pos.h + k, now_pos.w + l);
                            if (!is_exist[new_pos]) continue;
                            if (is_checked[new_pos.h][new_pos.w]) continue;
                            if (grid[new_pos.h][new_pos.w] == 0) continue;
                            Q.push(new_pos);
                            is_checked[new_pos.h][new_pos.w] = true;
                        }
                    }
                }
                land_cnt++;
            }
        }
    }
    cout << land_cnt << endl;
}

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    int W, H;
    while (true) {
        cin >> W >> H;
        if (W == 0 && H == 0) break;
        solve(W, H);
    }
    return 0;
}