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 <iostream>
#include <cmath>
#include <vector>
#include <string>
#include <map>
#include <algorithm>
#include <tuple>
#include <set>
#include <stack>
#include <queue>
#define REP(i, n) for(LL i = 0;i < n;i++)
#define REPR(i, n) for(LL i = n;i >= 0;i--)
#define FOR(i, m, n) for(LL i = m;i < n;i++)
#define FORR(i, m, n) for(LL i = m;i >= n;i--)
#define SORT(v, n) sort(v, v+n);
#define VSORT(v) sort(v.begin(), v.end());
#define pb(a) push_back(a)
#define all(x) (x).begin(),(x).end()
#define out(x, y) cout << x << " " << y << endl

#define INF 999999999
#define MOD 1000000007
using namespace std;
typedef long long LL;
//typedef LL int;
typedef pair<int, int> P;
typedef pair<LL, LL> LP;
typedef pair<int, P> PP;
typedef pair<LL, LP> LPP;
int dy[]={0, 0, 1, -1, 0};
int dx[]={1, -1, 0, 0, 0};

int main(){
    int w, h;
    while(cin >> w >> h, w + h){
        int c[51][51];
        REP(i, h){
            REP(j, w){
            cin >> c[i][j];
            }
        }

        int ans = 0;

        REP(i, h){
            REP(j, w){
                if(c[i][j] == 0) continue;
                else if(c[i][j] == 1){
                    queue<int> que;
                    que.push(i); que.push(j);
                    while(!que.empty()){
                        int x, y;
                        y = que.front(); que.pop();
                        x = que.front(); que.pop();
                        
                        // c[y][x] = 0;
                        
                        //??????
                        if(y-1 >= 0 && y-1 < h && x-1 >= 0 && x-1 < w && c[y-1][x-1] == 1){
                            que.push(y-1); que.push(x-1);
                            c[y-1][x-1] = 0;
                        }
                        //???
                        if(y-1 >= 0 && y-1 < h && x >= 0 && x < w && c[y-1][x] == 1){
                            que.push(y-1); que.push(x);
                            c[y-1][x] = 0;
                        }
                        //??????
                        if(y-1 >= 0 && y-1 < h && x+1 >= 0 && x+1 < w && c[y-1][x+1] == 1){
                            que.push(y-1); que.push(x+1);
                            c[y-1][x+1] = 0;
                        }
                        //???
                        if(y >= 0 && y < h && x-1 >= 0 && x-1 < w && c[y][x-1] == 1){
                            que.push(y); que.push(x-1);
                            c[y][x-1] = 0;
                        }
                        //???
                        if(y >= 0 && y < h && x+1 >= 0 && x+1 < w && c[y][x+1] == 1){
                            que.push(y); que.push(x+1);
                            c[y][x+1] = 0;
                        }
                        //??????
                        if(y+1 >= 0 && y+1 < h && x-1 >= 0 && x-1 < w && c[y+1][x-1] == 1){
                            que.push(y+1); que.push(x-1);
                            c[y+1][x-1] = 0;
                        }
                        //???
                        if(y+1 >= 0 && y+1 < h && x >= 0 && x < w && c[y+1][x] == 1){
                            que.push(y+1); que.push(x);
                            c[y+1][x] = 0;
                        }
                        //??????
                        if(y+1 >= 0 && y+1 < h && x+1 >= 0 && x+1 < w && c[y+1][x+1] == 1){
                            que.push(y+1); que.push(x+1);
                            c[y+1][x+1] = 0;
                        }
                    }
                    ans++;
                }
            }
        }

        cout << ans << endl;
    }
}

C++: #include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const double PI = acos(-1);
const ll MOD = 1000000007;

int w,h;
using Graph = vector<vector<int>>;

void dfs(Graph &G, int y, int x) {
  G[y][x] = 0;
  const vector<int> dy = {-1,-1,-1,0,0,1,1,1};
  const vector<int> dx = {-1,0,1,-1,1,-1,0,1};
  for (int i = 0; i < 8; i++) {
    int yy = y + dy[i];
    int xx = x + dx[i];
    if (yy < 0 || yy >= h || xx < 0 || xx >= w) continue;
    if (G[yy][xx] == 0) continue;
    dfs(G,yy,xx);
  }
  return;
}

int main() {
  while (true) {
    cin >> w >> h;
    if (w == 0 && h == 0) break;
    Graph G(h, vector<int>(w));
    for (int i = 0; i < h; i++) {
      for (int j = 0; j < w; j++) cin >> G[i][j];
    }
  
    int count = 0;
    for (int i = 0; i < h; i++) {
      for (int j = 0; j < w; j++) {
        if (G[i][j] == 0) continue;
        dfs(G,i,j);
        count++;
      }
    }
  
    cout << count << endl;
  }
}