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>
#include <vector>
#include <cstring>
using namespace std;

int dx[8] = {1,0,-1,0,1,1,-1,-1};
int dy[8] = {0,1,0,-1,1,-1,1,-1};
bool seen[60][60];
int H,W;

void dfs(const vector<vector<int> > &Grid, int y, int x){
    seen[y][x] = true;
    for(int i = 0; i < 8; i++){
        int ny = y + dy[i];
        int nx = x + dx[i];
        if(ny < 0 || ny >= H || nx < 0 || nx >= W) continue;
        if(seen[ny][nx]) continue;
        if(Grid[ny][nx] == 0) continue;
        dfs(Grid,ny,nx);
    }
}

int main(){
    while(true){
        cin >> W >> H;
        if(!H && !W) break;
        vector<vector<int> > Grid(H,vector<int>(W));
        for(int i = 0; i < H; i++){
            for(int j = 0; j < W; j++){
                cin >> Grid[i][j];
            }
        }
        memset(seen,false,sizeof(seen));
        int cnt = 0;
        for(int i = 0; i < H; i++){
            for(int j = 0; j < W; j++){
                if(Grid[i][j] == 0) continue;
                if(seen[i][j]) continue;
                dfs(Grid,i,j);
                cnt++;
            }
        }
        cout << cnt << endl;
    }
    return 0;
}

C++: #include<iostream>
#include<algorithm>
#include<cstring>
using namespace std;
int H,W,k[100][100],n[100][100],color=1,i,j,l,m,o,r;
int main(){while(true){memset(n,0,sizeof(n));r=0;cin>>H>>W;if(H==0){break;}for(i=0;i<H;i++){for(j=0;j<W;j++){cin>>k[i][j];}}
for(i=0;i<H;i++){for(j=0;j<W;j++){if(r==1){color++;}r=0;if(k[i][j]==1 && n[i][j]==0){n[i][j]=color;for(l=0;l<100;l++){
	for(m=0;m<H;m++){for(o=0;o<W;o++){if(n[m][o]==color){
		for(int p=-1;p<=1;p++){for(int q=-1;q<=1;q++){if(m-p>=0 && m-p<H){if(o-q>=0 && o-q<W){n[m][o]=color;}}}}
	}}}
}}}}
cout<<color<<endl;}
}

C++: #include <iostream>

using namespace std;

int w, h, cnt;
int island[51][51];
int dx[] = {1, 1, 0, -1, -1, -1,  0,  1};
int dy[] = {0, 1, 1,  1,  0, -1, -1, -1};

bool check(int nx, int ny){

  if(nx < 0 || w <= ny || ny < 0 || h < ny)return false;
  else return true;

}

void dfs(int sy, int sx){

  island[sy][sx] = 0;

  for(int i = 0 ; i < 8 ; i++){
    int nx = sx + dx[i];
    int ny = sy + dy[i];
    if(!check(nx, ny)) continue;
    if(island[ny][nx]) dfs(ny, nx);
  }
}

int main(void){

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

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

    int cnt = 0;
    for(int i = 0 ; i < h ; i++){
      for(int j = 0 ; j < w ; j++){
	if(island[i][j]){
	  dfs(i, j);
	  cnt++;
	}
      }
    }
    cout << cnt << endl;
  }
  return 0;
}

C++: #include<iostream>
#include<cmath>
#include<cstdio>
#include<algorithm>
#include<vector>
#include<cstring>

using namespace std;

#define INF 999999999

int map[52][52];
bool ch[52][52];
int ans;

void dfs(int map[52][52], bool c[52][52], int x, int y){
	//cout << x << " " << y << " " << ans << endl;
	c[x][y] = 1;
	if(map[x-1][y]==1 && c[x-1][y]==0) dfs(map,c,x-1,y);
	if(map[x-1][y-1]==1 && c[x-1][y-1]==0) dfs(map,c,x-1,y-1);
	if(map[x-1][y+1]==1 && c[x-1][y+1]==0) dfs(map,c,x-1,y+1);
	if(map[x+1][y]==1 && c[x+1][y]==0) dfs(map,c,x+1,y);
	if(map[x+1][y-1]==1 && c[x+1][y-1]==0) dfs(map,c,x+1,y-1);
	if(map[x+1][y+1]==1 && c[x+1][y+1]==0) dfs(map,c,x+1,y+1);
	if(map[x][y-1]==1 && c[x][y-1]==0) dfs(map,c,x,y-1);
	if(map[x][y+1]==1 && c[x][y+1]==0) dfs(map,c,x,y+1);
}

int main(){
	int i, j, w, h;
	while(1){
		cin >> w >> h;
		if(!w) break;
		for(i=0;i<=h+1;i++){
			for(j=0;j<=w+1;j++){
				if(i==0||i==h+1||j==0||j==w+1)map[i][j]=0;
				else cin >> map[i][j];
				ch[i][j] = 0;
			}
		}
		ans = 0;
		for(i=1;i<=h;i++){
			for(j=1;j<=w;j++){
				if(map[i][j]&&!ch[i][j]){
					dfs(map,ch,i,j);
					ans++;
				}
			}
		}
		
		cout << ans << endl;
	}
	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;
int m[50][50];

void solve(int x,int y){
	if(m[y][x] == 1){
		m[y][x] = 0;
		for(int i=-1;i<2;i++){
			for(int j=-1;j<2;j++){
				if(i==0&&j==0){
					continue;
				}
				if(y+i >= 0 && y+i < h && x+i >= 0 && x+i < w){
					solve(x+j,y+i);
				}
			}
		}
	}
}

int main(){
	while(true){
		int count=0;

		cin >> w >> h;
		if(w==0&&h==0){
			break;
		}

		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){
					solve(j,i);
					count++;
				}
			}
		}

		cout << count << endl;
	}
}