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<stack>
#include<queue>
#include<utility>
using namespace std;
bool find1(vector< vector<int> >& C,vector< vector<int> >& check,int* findh,int* findw)
{
  for(int i = 0;i < C.size();++i)
    for(int j = 0;j < C[0].size();++j)
      if(C[i][j] == 1 && check[i][j] == 0){
	*findh = i;
	*findw = j;
	return true;
      }
  return false;
}
bool find2(vector< vector<int> >& C,vector< vector<int> >& check,int* findh,int* findw)
{
  if(C[*findh - 1][*findw - 1] == 1 && check[*findh - 1][*findw - 1] == 0){
    *findh -= 1;
    *findw -= 1;
    return true;
  }
  else if(C[*findh - 1][*findw] == 1 && check[*findh - 1][*findw] == 0){
    *findh -= 1;
    return true;
  }
  else if(C[*findh - 1][*findw + 1] == 1  && check[*findh - 1][*findw + 1] == 0){
    *findh -= 1;
    *findw += 1;
    return true;
  }
  else if(C[*findh][*findw - 1] == 1 && check[*findh][*findw - 1] == 0){
    *findw -= 1;
    return true;
  }
  else if(C[*findh][*findw + 1] == 1 && check[*findh][*findw + 1] == 0){
    *findw += 1;
    return true;
  }
  else if(C[*findh + 1][*findw - 1] == 1 && check[*findh + 1][*findw - 1] == 0){
    *findh += 1;
    *findw -= 1;
    return true;
  }
  else if(C[*findh + 1][*findw] == 1 && check[*findh + 1][*findw] == 0){
    *findh += 1;
    return true;
  }
  else if(C[*findh + 1][*findw + 1] == 1 && check[*findh + 1][*findw + 1] == 0){
    *findh += 1;
    *findw += 1;
    return true;
  }
  else return false;
}
int main()
{
  int w,h,findh,findw;
  stack< pair<int,int> > finish;
  queue<int> answer;
  while(cin >> w >> h && !(w == 0 && h == 0)){
    int howmany = 0;
    vector< vector<int> > C(h + 2,vector<int>(w + 2,0)),check(h + 2,vector<int>(w + 2,0)); 
    for(int i = 1;i <= h;++i)
      for(int j = 1;j <= w;++j)
	cin >> C[i][j];
    while(find1(C,check,&findh,&findw)){
      check[findh][findw] = 1;
      finish.push(make_pair(findh,findw));
      while(!finish.empty()){
	findh = finish.top().first;
	findw = finish.top().second;
	while(find2(C,check,&findh,&findw)){
	  finish.push(make_pair(findh,findw));
	  check[findh][findw] = 1;
	}
	finish.pop();
      }
      ++howmany;
    }
    answer.push(howmany);
  }
  for(;!answer.empty();answer.pop())
    cout << answer.front() << endl;
}

C++: #include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i=0;i<n;i++)

int n,m;
int v[100][100];
bool used[100][100];
int dir[8][2]={{1,0},{1,1},{0,1},{-1,1},{-1,0},{-1,-1},{0,-1},{1,-1}};

void dfs(int i, int j){
    if((v[i][j]==0) || (used[i][j]==true)){
        return;
    }
    used[i][j]=true;
    rep(k,8){
        if(i+dir[k][0]<=n-1 && 0<=i+dir[k][0]){
            if(j+dir[k][1]<=m-1 && 0<=j+dir[k][1]){
                dfs(i+dir[k][0],j+dir[k][1]);
            }
        }
    }
    return;
}

int main(){
    vector<int> ans;

    while(true){
        cin >> m >> n;
        if(n==0 && m==0)break;
        rep(i,n){
            rep(j,m){
                cin >> v[i][j];
            }
        }

        int res=0;
        rep(i,n){
            rep(j,m){
                used[i][j]=false;
            }
        }
        rep(i,n){
            rep(j,m){
                if(v[i][j]==1 && used[i][j]==false){
                    dfs(i,j);
                    res++;
                }
            }
        }
        ans.push_back(res);
    }

    rep(i,ans.size()){
        cout << ans[i] << endl;
    }
    return 0;
}

C++: #include<iostream>
using namespace std;
bool ban[52][52];
	void dfs(int x,int y){
		ban[y][x]=0;
		for(int i=-1;i<=1;i++){
			for(int j=-1;j<=1;j++){
				if(ban[y+i][x+j]==true){
					dfs(x+j,y+i);
				}
			}
		}
	}
int main(){
	int w,h;
	while(cin>>w>>h,h+w!=0){
		for(int i=0;i<h;i++)ban[i][0]=0,ban[i][h+1]=0;//番兵
		for(int i=0;i<w;i++)ban[0][i]=0,ban[0][w+1]=0;//
		for(int i=1;i<=h;i++){
			for(int j=1;j<=w;j++)cin>>ban[i][j];
		}
	int cnt=0;
	for(int i=1;i<=h;i++){
		for(int j=1;j<=w;j++){
			if(ban[i][j]==true){
				dfs(j,i);
				cnt++;
			}
		}	
	}
		cout<<cnt<<endl;
	}
	return 0;
}

C++: #include <bits/stdc++.h>
#define int long long
using namespace std;
int d[51][51];
int used[51][51];
typedef pair<int,int> P;

signed main(){
  int W,H;
  std::vector<int> fans;
  while(true){
    cin>>W>>H;if(W==0&&H==0)break;
    for(int i=0;i<H;i++)for(int j=0;j<W;j++)cin>>d[i][j];
    for(int i=0;i<51;i++)for(int j=0;j<51;j++)used[i][j]=0;
    int ans=0;
    for(int i=0;i<H;i++){
      for(int j=0;j<W;j++){
        if(used[i][j]||d[i][j]==0)continue;
        used[i][j]=1;ans++;
        queue<P> que;que.push(P(i,j));
        while(que.size()){
          P p=que.front();que.pop();
          for(int k=max(0LL,p.first-1);k<=min(H-1,p.first+1);k++){
            for(int l=max(0LL,p.second-1);l<=min(W-1,p.second+1);l++){
              if(used[k][l]==0&&d[k][l]){
                used[k][l]++;que.push(P(k,l));
              }
            }
          }
        }
      }
    }
    fans.push_back(ans);
  }
  for(int i=0;i<fans.size();i++)cout<<fans[i]<<endl;
}