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;
typedef long long ll;
const ll INF = 1e18;
const int inf = 1e9;
#define rep(i, a, b) for (int i = a; i < b; i++)
#define per(i, b, a) for (int i = a - 1; i >= b; i--)
using Graph = vector<vector<int>>;
using pint = pair<int, int>;
int dx[4] = {1, 0, -1, 0}, dy[4] = {0, 1, 0, -1};
int dxx[8] = {1, 1, 1, 0, 0, -1, -1, -1}, dyy[8] = {-1, 0, 1, -1, 1, -1, 0, 1};

bool seen[55][55];
int ans = 0;
int c[55][55];

bool dfs (int y, int x, int w, int h) {
    if (seen[y][x] || c[y][x] == 0) return false;
    seen[y][x] = true;
    rep (i, 0, 8) {
        int ny = y + dyy[i], nx = x + dxx[i];
        if (ny >= 0 && ny < h && nx >= 0 && nx < w && !seen[ny][nx] &&
            c[ny][nx] == 1) {
            dfs (ny, nx, w, h);
        }
    }
    return true;
}

int main() {
    int w, h;
    while (1) {
        cin >> w >> h;
        if (w == 0 && h == 0) break;
        rep (i, 0, h) rep (j, 0, w) cin >> c[i][j];
        rep (i, 0, h) rep (j, 0, w) seen[i][j] = 0;
        int ans = 0;
        rep (i, 0, h) {
            rep (j, 0, w) {
                if (dfs (i, j, w, h)) {
                    // cout << i << " " << j << "\n";
                    ans++;
                }
            }
        }
        cout << ans << "\n";
    }
}

C++: #include<iostream>
using namespace std;
int dx[]={1,0,-1,0,1,-1,-1,1};
int dy[]={0,1,0,-1,1,-1,1,-1};
int field[150][150];
void dfs(int x, int y);
int main(){
  int h,w;
  while(cin >>h>>w,h||w){
    for(int i=0; i<150; i++) for(int j=0; j<150; j++) field[i][j] = 0;
    for(int i=0; i<w; i++) for(int j=0; j<h; j++) cin >>field[i+50][j+50];
    int ans = 0;
    for(int i=0; i<w; i++){
      for(int j=0; j<h; j++){
	if(field[i+50][j+50] == 1){
	  dfs(i+50,j+50);
	  ans++;
	}
      }
    }
    cout <<ans<<endl;
  }
  return 0;
}
void dfs(int x, int y){
  field[x][y] = 0;
  for(int i=0; i<8; i++) if(field[x+dx[i]][y+dy[i]] == 1) dfs(x+dx[i],y+dy[i]);
}

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

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

int main() {
	int w, h, ans, x, y;
	int c[52][52], f[52][52];
	queue< pair<int, int> > q;
	while(1) {
		cin >> w >> h;
		if(!w&&!h) break;
		for(int i=0; i<h+2; ++i) for(int j=0; j<w+2; ++j) {
			c[i][j] = 0; f[i][j] = 0;
		}
		ans = 0;
		
		for(int i=1; i<=h; ++i) for(int j=1; j<=w; ++j) {
			cin >> c[i][j];
		}
		for(int i=1; i<=h; ++i) for(int j=1; j<=w; ++j) {
			if(c[i][j]&&!f[i][j]) {
				ans++;
				q.push( pair<int, int>(i, j) );
				while(!q.empty()) {
					y = q.front().first; x = q.front().second;
					q.pop();
					f[y][x] = 1;
					for(int k=0; k<8; ++k) {
						if(c[y+dy[k]][x+dx[k]]&&!f[y+dy[k]][x+dx[k]]) {
							q.push( pair<int, int>(y+dy[k], x+dx[k]) );
						}
					}
				}
			}
		}
		cout << ans << endl;
	}
}

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

int w,h;
int c[50][50];
vector<vector<int> > visited;
int dx[]={1,1,0,-1,-1,-1,0,1};
int dy[]={0,-1,-1,-1,0,1,1,1};

bool dfs(int x,int y){
    if(visited[x][y]) return false;
    visited[x][y]=1;

    for(int d=0;d<8;d++){
        int i=x+dx[d];
        int j=y+dy[d];
        if(0<=i&&i<h&&0<=j&&j<w){
            if(c[i][j]){
                dfs(i,j);
            }  
        }
    }
    return true;
}

int main(){
    visited.assign(50,vector<int>(50,0));
    cin>>w>>h;
    for(int i=0;i<h;i++){
        for(int j=0;j<w;j++){
            cin>>c[i][j];
        }
    }
    int cnt=0;
    for(int i=0;i<h;i++){
        for(int j=0;j<w;j++){
            if(c[i][j]){
                cnt+=dfs(i,j);
            }
        }
    }

    cout<<cnt<<endl;
    return 0;
}

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

int w, h, c[51][51];
const int dx[8] = {-1,-1,-1, 0, 0,+1,+1,+1};
const int dy[8] = {-1, 0,+1,-1,+1,-1, 0,+1};


void dfs(int x, int y){
	c[y][x] = 0;
	for(int i = 0; i < 8; i++){
		int mx = x + dx[i], my = y + dy[i];
		if( mx < 0 || my < 0 || w <= mx || h <= my ) continue;
		
		if( c[my][mx] == 1 ) dfs(mx, my);
	}
}

int main(){
	while( cin >> w >> h , w || h ){
		for(int y = 0; y < h; y++){
			for(int x = 0; x < w; x++){
				cin >> c[y][x];
			}
		}
		int ans = 0;
		for(int y = 0; y < h; y++){
			for(int x = 0; x < w; x++){
				if( c[y][x] == 1 ){
					ans++;
					dfs(x, y);
				}
			}
		}
		cout << ans << endl;
	}
}

C++: #include<stdio.h>
int h,w;
int map[50][50];
void func(int ,int);
int main(void){
	while(1){
		scanf("%d %d",&w,&h);
		if(h==0 && w==0){
			break;
		}
		int i,j;
		for(i=0;i<h;i++){
			for(j=0;j<w;j++){
				scanf("%d",&map[i][j]);
			}
		}
		/*for(i=0;i<h;i++){
			for(j=0;j<w;j++){
				printf("%d ",map[i][j]);
			}
			printf("\n");
		}*/
		int cnt=0;
		for(i=0;i<h;i++){
			for(j=0;j<w;j++){
				if(map[i][j]==1){
					map[i][j]=0;
					func(i,j);
					cnt++;
				}
			}
		}
		printf("%d\n",cnt);
		cnt=0;
	}
	return 0;
}
void func(int y,int x){
	int dy[8]={1,0,0,-1,-1,-1,1,1},dx[8]={0,1,-1,0,-1,1,-1,1};
	int i,j,xx,yy;
	for(i=0;i<8;i++){
		yy=y+dy[i];
		xx=x+dx[i];
		if(yy>=0 && yy<h && xx>=0 && xx<w && map[yy][xx]==1){
			map[yy][xx]=0;
			func(yy,xx);
		}
	}
}