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 <map>
#include <set>
using namespace std;

int field[52][52];
int memo[52][52];

void dfs(int j, int i){
	if( memo[i][j] || !field[i][j] ) return;
	memo[i][j] = 1;
	dfs(j-1, i-1);
	dfs(j, i-1);
	dfs(j+1, i-1);
	dfs(j-1, i);
	dfs(j+1, i);
	dfs(j-1, i+1);
	dfs(j, i+1);
	dfs(j+1, i+1);
}

int main(void){
	int w, h;
	while( cin>>w>>h, w||h ) {
		for( int i=0; i<h; ++i ) {
			for( int j=0; j<w; ++j ) {
				cin>>field[i][j];
				memo[i][j] = 0;
			}
		}
		int ans = 0;
		for( int i=0; i<h; ++i ) {
			for( int j=0; j<w; ++j ) {
				if( field[i][j] && !memo[i][j] ){
					dfs( j, i );
					++ans;
				}
			}
		}
		cout<<ans<<endl;
	}
	return 0;
}

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

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

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

void solve(){
  int res=0;
  for(int i=0;i<h;i++){
    for(int j=0;j<w;j++){
      if(filed[i][j]==1){
	dfs(i,j);
	res++;
      }
    }
  }
  cout<<res<<endl;
}

int main(){
  while(1){
    cin>>w>>h;
    if(w+h==0)break;
    for(int i=0;i<h;i++){
      for(int j=0;j<w;j++){
	cin>>filed[i][j];
      }
    }
    solve();
  }
  return 0;
}

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

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

int w, h, c[55][55], ans;
bool is_search[55][55];
int vx[8] = {0, -1, -1, -1, 0, 1, 1, 1},
    vy[8] = {-1, -1, 0, 1, 1, 1, 0, -1};


void bfs(int x, int y) {
    queue<pair<int, int> > que;
    que.push(make_pair(x, y));
    is_search[x][y] = true;

    while (!que.empty()) {
        pair<int, int> p = que.front(); que.pop();
        //cout << p.first << " " << p.second << endl;
        rep(i,8) {
            int nx, ny;
            nx = p.first + vx[i], ny = p.second + vy[i];
            if (0 <= nx && nx < h && 0 <= ny && ny < w &&
                c[nx][ny] == 1 && is_search[nx][ny] == false) {
                   que.push(make_pair(nx, ny));
                   is_search[nx][ny] = true;
            }
        }
    }

}

int main(void) {
    cin.tie(0);
    ios::sync_with_stdio(false);

    while (cin >> w >> h, w | h) {
        memset(c, 0, sizeof(c));
        memset(is_search, false, sizeof(is_search));
        ans = 0;
        rep(i,h) {
            rep(j,w) {
                cin >> c[i][j];
            }
        }

        rep(i,h) {
            rep(j,w) {
                if (is_search[i][j] == false && c[i][j] == 1) {
                    bfs(i,j);
                    ans++;
                }
            }
        }

        cout << ans << endl;
    }

    return 0;
}

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

vector<int> dx = {1, 0, -1, 0, 1, 1, -1, -1}, dy = {0, 1, 0, -1, 1, -1, 1, -1};

void bfs(int i, int j, int h, int w, vector<vector<int>> &c) {
  queue<pair<int, int>> q;
  q.push(make_pair(i, j));
  c.at(i).at(j) = 0;
  
  while (!q.empty()) {
    pair<int, int> p = q.front();
    q.pop();
    for (int i = 0; i < 8; i++) {
      if (p.first + dx[i] >= 0 && p.first + dx[i] < h
       && p.second + dy[i] >= 0 && p.second + dy[i] < w) {
        if (c.at(p.first + dx[i]).at(p.second + dy[i]) == 1) {
          c.at(p.first + dx[i]).at(p.second + dy[i]) = 0;
          q.push(make_pair(p.first + dx[i], p.second + dy[i]));
        }
      }
    }
  }
  
  return;
}

int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  
  while (true) {
    int w, h;
    cin >> w >> h;
    if (w + h == 0) break;
    
    vector<vector<int>> c(h, vector<int>(w));
    for (int i = 0; i < h; i++) {
      for (int j = 0; j < w; j++) {
        cin >> c.at(i).at(j);
      }
    }
    
    int ans = 0;
    for (int i = 0; i < h; i++) {
      for (int j = 0; j < w; j++) {
        if (c.at(i).at(j) == 1) {
          bfs(i, j, h, w, c);
          ans++;
        }
      }
    }
    
    cout << ans << '\n';
  }
}