Go: ///
// File:  1160.go
// Author: ymiyamoto
//
// Created on Sun Mar  4 20:45:57 2018
//
package main

import (
	"fmt"
)

var w, h int
var graph [][]string

func dfs(visited [][]bool, x, y int) {
	visited[x][y] = true

	for i := -1; i <= 1; i++ {
		for j := -1; j <= 1; j++ {
			dx := x + i
			dy := y + j
			if 0 <= dx && dx < h && 0 <= dy && dy < w && graph[dx][dy] == "1" && !visited[dx][dy] {
				dfs(visited, dx, dy)
			}
		}
	}
}

func main() {
	for {
		fmt.Scan(&w, &h)
		if w == 0 && h == 0 {
			break
		}

		graph = make([][]string, h)
		for i := range graph {
			graph[i] = make([]string, w)
		}

		for i := 0; i < h; i++ {
			for j := 0; j < w; j++ {
				var s string
				fmt.Scan(&s)
				graph[i][j] = s
			}
		}

		visited := make([][]bool, h)
		for i := range visited {
			visited[i] = make([]bool, w)
		}

		count := 0
		for i := range graph {
			for j := range graph[i] {
				if graph[i][j] == "1" && !visited[i][j] {
					dfs(visited, i, j)
					count++
				}
			}
		}

		fmt.Println(count)
	}
}

C++: #include <bits/stdc++.h>
using namespace std;
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define rep(i,n) FOR(i,0,n)
#define repr(i,n) for(int i=(n)-1;0<=i;--i)
#define each(e,v) for(auto&& e:(v))
#define all(v) begin(v),end(v)
#define dump(x) cerr<<#x<<": "<<(x)<<endl
#define INF 100000000
#define IINF 9999999999999;
using vint = vector<int>;
using ll = long long;
using vll = vector<ll>;
template <class T> void chmin(T& a, const T& b) { a = min(a, b); }
template <class T> void chmax(T& a, const T& b) { a = max(a, b); }

int prime[25] = {2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97};
long long int dp[101][20] = {0};

bool earth[51][51];

void erase_island(int h, int w) {
    earth[h][w] = false;
    //cout << "# " << h << " " << w << endl;
    if(earth[h - 1][w - 1]) erase_island(h - 1, w - 1);
    if(earth[h - 1][w]) erase_island(h - 1, w);
    if(earth[h - 1][w + 1]) erase_island(h - 1, w + 1);
    if(earth[h][w + 1]) erase_island(h, w + 1);
    if(earth[h + 1][w + 1]) erase_island(h + 1, w + 1);
    if(earth[h + 1][w]) erase_island(h + 1, w);
    if(earth[h + 1][w - 1]) erase_island(h + 1, w - 1);
    if(earth[h][w - 1]) erase_island(h, w - 1);
}

int main() {
    while(true) {
        int w, h;
        cin >> w >> h;
        if(w == 0 && w == 0) break;
        rep(i, h) rep(j, w) {
                int temp;
                cin >> temp;
                if(temp == 0) earth[i][j] = false;
                else earth[i][j] = true;
            }

        int ans = 0;
        rep(i, h) rep(j, w) {
                if(earth[i][j]) erase_island(i , j), ++ans;
            }

        cout << ans << endl;
    }

    return 0;
}

C++: #include<bits/stdc++.h>
#define _ ios_base::sync_with_stdio(0);cin.tie(0);
#define REP(i,n) for(int i=0;i<(int)(n);i++)

using namespace std;

int c[52][52];

bool dfs(int x,int y){
  if(c[x][y]==0) return false;
  c[x][y]=0;
  for(int i=-1;i<=1;i++){
    for(int j=-1;j<=1;j++){
      if((i|j)!=0&&c[x+i][y+j]!=0)
	dfs(x+i,y+j);
    }
  }
  return true;
}

int main(){ _;
  int w,h;
  while(cin>>w>>h,!(w==0&&h==0)){
    int count=0;
    REP(j,h+2)REP(i,w+2) c[i][j]=0;
    REP(j,h)REP(i,w) cin>>c[i+1][j+1];
    REP(j,h)REP(i,w)
      if(dfs(i+1,j+1))
	count++;
    cout<<count<<endl;
  }
}

C++: #include<iostream>
#include<vector>
using namespace std;
int dx[8]={0,1,0,-1,1,1,-1,-1};
int dy[8]={1,0,-1,0,1,-1,1,-1};

bool dfs(int sx,int sy,vector<vector<bool> >&c){
    if(c[sx][sy]==false) return false;
    c[sx][sy]=false;
    for(int i=0;i<8;i++){
        int nx=sx+dx[i];
        int ny=sy+dy[i];
        bool flag=dfs(nx,ny,c);
    }
    return true;
}

int main(void){
    int h,w,temp;
    while(1){
        cin>>w>>h;
        if(w==0) break;
        vector<vector<bool> > c(h+2,vector<bool>(w+2,false)) ;
        for(int i=1;i<=h;i++){
            for(int j=1;j<=w;j++){
                cin>>temp;
                if(temp==1) c[i][j]=true;
            }
        }
        int t=0;
        for(int i=1;i<=h;i++){
            for(int j=1;j<=w;j++){
                bool flag=dfs(i,j,c);
                if(flag) t++;
            }
        }
        cout<<t<<endl;
    }
    return 0;
}

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

int MAP(vector<vector<int> > &m, int i, int j){
	int w = m[0].size();
	int h = m.size();

	if(!(0 <= i && i < h && 0 <= j && j < w)){
		return 0;
	}

	if(m[i][j] == 0){
		return 0;
	}
	else if(m[i][j] = 1){
		m[i][j] = 0;
		MAP(m, i - 1, j - 1);
		MAP(m, i, j - 1);
		MAP(m, i + 1, j - 1);
		MAP(m, i - 1, j);
		MAP(m, i + 1, j);
		MAP(m, i - 1, j + 1);
		MAP(m, i, j + 1);
		MAP(m, i + 1, j + 1);
	}
	return 1;
}

int main(){
	int w, h;

	while(true){
		int count = 0;
		cin >> w >> h;

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

		vector<vector<int> > map(h, vector<int>(w, 0));

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

		for(int i = 0; i < h; i++){
			for(int j = 0; j < w; j++){
				count += MAP(map, i , j);
			}
		}

		cout << count << endl;
	}
}

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

int land[50][50], flag[50][50];
int w, h;
int xroot[] = {0,0,1,1,1,-1,-1,-1};
int yroot[] = {1,-1,0,-1,1,0,1,-1};
int cnt = 1;


void dfs(int x, int y){


  if(land[y][x] != 1) return;
  land[y][x] = cnt;

  for(int i = 0; i < 8; i++){
    int nx = x + xroot[i], ny = y + yroot[i];
    if(ny >= h || nx >= w || ny < 0 || nx < 0) continue;
    // cout << nx << " " << ny << endl;
    dfs(nx,ny);
  }
}

int main(){

  while(cin >> w >> h && (w || h)){
    cnt = 1;
    memset(flag,0,sizeof(flag));

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



    for(int i = 0; i < h; i++){
      for(int j = 0; j < w; j++){ 
	if(land[i][j] == 1){
	  cnt++;
	  dfs(j,i);
	}
      }
    }
    cout << cnt - 1 << endl;

  }



  return 0;
}

C++: #include<bits/stdc++.h>

#define rep(i,N) for(int i=0;i<N;i++)
#define rep2(i,N) for(int i=1;i<=N;i++)
using namespace std;
long long  INF=1e18;
long long mod=1e9+7;
int maze[55][55]={};
bool reached[55][55]={};
int dx[8]={0,1,0,-1,1,-1,1,-1};
int dy[8]={1,0,-1,0,1,-1,-1,1};
int w,h;
int islands;

void search(int nowy,int nowx,bool start){

    if(reached[nowy][nowx]||maze[nowy][nowx]==0)return;

    if(start)islands++;

    reached[nowy][nowx]=true;
    //cout<<nowy<<" "<<nowx<<" "<<endl;
    rep(i,8)
    {
        int nx=nowx+dx[i];
        int ny=nowy+dy[i];

        if(nx<1 || nx>w || ny<1 || ny>h||reached[ny][nx]|| !maze[ny][nx])continue;

        search(ny,nx,false);
    }
    //cout<<islands<<" end"<<endl;
    return;
}
int main(){
    

    while(1){
    
    cin>>w>>h;
    if(w==0 && h==0)break;
    //cout<<w<<" "<<h<<endl;
    islands=0;

    rep2(i,50)rep2(k,50){
        reached[i][k]=false;
        maze[i][k]=0;
    }
    rep2(i,h)rep2(k,w){
        int t;
        cin>>t;
        maze[i][k]=t;
    }

    rep2(i,h)rep2(k,w)search(i,k,true);

    cout<<islands<<endl;
    
    }
    return 0;

}
/*


*/