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;
typedef long long ll;
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define INF (1LL<<50)
#define MOD 1000000007

typedef vector<vector<int>> Graph;
int x[] = {-1,-1,-1,0,0,0,1,1,1};
int y[] = {-1,0,1,-1,0,1,-1,0,1};
int W,H;
Graph C(51,vector<int>(51));
Graph seen(51,vector<int>(51));

void dfs(Graph &C, Graph &seen, int h, int w){
    seen[h][w] = 1;
    rep(i,9){
        int next_h,next_w;
        next_h = h+y[i];
        next_w = w+x[i];
        if(next_h<0||next_h>=H||next_w<0||next_w>=W)continue;
        if(C[next_h][next_w]==1&&seen[next_h][next_w]==0){
            dfs(C,seen,next_h,next_w);
        }
    }
}

int main(){
    while(true){
        cin >> W >> H;
        if(W==0&&H==0){
            return 0;
        }
        rep(i,H)rep(j,W){
            cin >> C[i][j];
            seen[i][j]=0;
        } 
        int num=0;
        rep(i,H){
            rep(j,W){
                if(C[i][j]==0 || seen[i][j]==1) continue;
                num++;
                dfs(C,seen,i,j);
            }
        }
        cout << num << endl;
    }
    return 0;
}

C++: #include <algorithm>
#include <iostream>
#include <string>
#include <cstring>
#include <cassert>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <deque>
#include <iomanip>
#include <limits>
#include <map>
#include <queue>
#include <stack>
#include <vector>

#define FOR(i,k,n) for(int (i) = (k); (i) < (n); ++(i))
#define rep(i,n) FOR(i,0,n)
#define pb push_back
#define all(v) begin(v), end(v)
#define debug(x) cerr << #x << ": " << x << endl
#define debug2(x,y) cerr << #x << ": " << x << ", " << #y << ": " << y << endl

using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> i_i;
typedef pair<i_i, int> p_i;
typedef vector<int> vi;
typedef vector< vector<int> > vvi;
template<class T> using vv=vector< vector<T> >;
typedef deque<int> di;
typedef deque< deque<int> > ddi;

int dx[3] = {-1,0,1}, dy[3] = {-1,0,1};

int c[55][55] = {};

void dfs(i_i p) {
    c[p.first][p.second] = 0;
    rep(i,3) {
        rep(j,3) {
            if(c[p.first+dx[i]][p.second+dy[j]] == 1) {
                dfs(make_pair(p.first+dx[i], p.second+dy[j]));
            }
        }
    }
}

int main() {
    int w,h;
    while(cin >> w >> h,w) {
        memset(c,0,sizeof(c));
        FOR(i,1,h+1) {
            FOR(j,1,w+1) {
                cin >> c[i][j];
            }
        }
        int sum = 0;
        FOR(i,1,h+1) {
            FOR(j,1,w+1) {
                if(c[i][j] == 1) {
                    dfs(make_pair(i,j));
                    sum += 1;
                }
            }
        }
        cout << sum << endl;
    }
	return 0;
}

C++: #include<bits/stdc++.h>
#define rep(i,a,b) for(int i=int(a);i<int(b);++i)
using namespace std;
typedef long long ll;
int INF = (1LL << 30) - 1;
int MOD = 1e9+7;
int H,W;
void dfs(int h,int w,vector<vector<int> > &table){
    //cout << h << " " << w << endl;
    table[h][w] = 0;
    int dx[] = {-1,-1,-1,0 ,0,1 ,1,1};
    int dy[] = {-1,0 ,1 ,-1,1,-1,0,1};
    rep(i,0,8){
        int nx = w + dx[i];
        int ny = h + dy[i];
        if (nx >= W || nx < 0 || ny >= H || ny < 0) continue;
        if(table[ny][nx])dfs(ny,nx,table);
    }
}
main(){
    cin >> W >> H;
    vector< vector<int> > table;
    while(W){
        table = vector< vector<int> > (H,vector<int>(W) );
        rep(i,0,H)rep(j,0,W)cin >> table[i][j];
        rep(i,0,H)rep(j,0,W)cout << table[i][j] << " \n"[j==W-1];
        int cnt = 0;
        rep(i,0,H)rep(j,0,W){
            if(table[i][j] == 1){
                //cout << i << " " << j << endl;
                dfs(i,j,table);
                cnt++;
            }
        }
        cout << cnt << endl;
        cin >> H >> W;
    }
}

C++: #include <cstdio>
#include <iostream>
 
using namespace std;
 
int main(void){
    
    while(1){
        
        int w, h;
        
        cin >> w >> h;
        if(w == 0 && h == 0) break;
        
        int map[52][52] = { {0} };
        int check[52][52] = { {0} };
        
        int i, j;
        for(j=1; j<=h; j++){
            for(i=1; i<=w; i++){
                cin >> map[j][i];
            }
        }
        
        
        int label = 1;
        
        int x, y;
        for(y=1; y<=h; y++){
            for(x=1; x<=w; x++){
                if(map[y][x] == 1){
                    if(check[y][x-1] || check[y-1][x-1] || check[y-1][x] || check[y-1][x+1]){
                        int min;
                        if(check[y][x-1]){
                            min = check[y][x-1];
                        } else {
                            min = 2500;
                        }
                        for(int k=x-1; k<=x+1; k++){
                            if(check[y-1][k] != 0 && check[y-1][k] < min) min = check[y-1][k];
                        }
                        check[y][x] = min;
                    } else {
                        check[y][x] = label;
                        label++;
                    }
                }
            }
        }
        
        
        for(y=h; y>0; y--){
            for(x=w; x>0; x--){
                if(check[y][x]){
                    int min = check[y][x];
                    for(int n=y-1; n<=y+1; n++){
                        for(int k=x-1; k<=x+1; k++){
                            if(check[n][k] != 0 && check[n][k] < min) min = check[n][k];
                        }
                    }
                    check[y][x] = min;
                }
            }
        }
        
        int count = 0;
        
        for(y=1; y<=h; y++){
            for(x=1; x<=w; x++){
                if(count < check[y][x]) count = check[y][x];
            }
        }
        
        cout << count << endl;
        
    }
    
    
    return 0;
}