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>

#define M_PI       3.14159265358979323846   // pi

using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef vector<ll> VI;
typedef pair<ll, ll> P;
typedef tuple<ll, ll, ll> t3;
typedef tuple<ll, ll, ll, ll> t4;
typedef tuple<ll, ll, ll, ll, ll> t5;

#define rep(a,n) for(ll a = 0;a < n;a++)
#define repi(a,b,n) for(ll a = b;a < n;a++)

using namespace std;

static const ll INF = 1e15;

struct UnionFind {
public:
	vector <ll> par; // 
	vector <ll> siz; // 

	UnionFind() {}

	UnionFind(ll sz_) : par(sz_), siz(sz_, 1LL) {
		for (ll i = 0; i < sz_; ++i) par[i] = i;
	}
	void init(ll sz_) {
		par.resize(sz_);
		siz.assign(sz_, 1LL);
		for (ll i = 0; i < sz_; ++i) par[i] = i;
	}

	ll root(ll x) {
		while (par[x] != x) {
			x = par[x] = par[par[x]];
		}
		return x;
	}

	bool merge(ll x, ll y) {
		x = root(x);
		y = root(y);
		if (x == y) return false;
		if (siz[x] < siz[y]) swap(x, y);
		siz[x] += siz[y];
		par[y] = x;
		return true;
	}

	bool issame(ll x, ll y) {
		return root(x) == root(y);
	}

	ll size(ll x) {
		return siz[root(x)];
	}
};

int main() {
	while (true) {
		ll w, h;
		cin >> w >> h;
		if (w == 0 && h == 0) return 0;
		vector<vector<int>> grid(h, vector<int>(w, 0));
		rep(i, h) {
			rep(j, w) {
				cin >> grid[i][j];
			}
		}

		vector<vector<int>> root(h, vector<int>(w, -1));

		function<void(int, int, int)> dfs = [&](int x, int y, int parent) {
			if (root[y][x] >= 0) return;
			if (!grid[y][x]) return;
			root[y][x] = parent;
			P shifts[] = {
				{0,1},{-1,1},{-1,0},{-1,-1},
				{0,-1},{1,-1},{1,0},{1,1},
			};
			for (auto p : shifts) {
				auto nx = x + p.first;
				auto ny = y + p.second;
				if (nx >= 0 && nx < w) {
					if (ny >= 0 && ny < h) {
						if(grid[ny][nx]) dfs(nx, ny, parent);
					}
				}
			}
		};
		rep(i, h) {
			rep(j, w) {
				dfs(j, i, i * w + j);
			}
		}

		unordered_set<ll> u;
		rep(i, h) {
			rep(j, w) {
				if (grid[i][j]) {
					u.insert(root[i][j]);
				}
			}
		}
		cout << u.size() << endl;
	}
	return 0;
}

C++: #include<iostream>
#include<cstdio>
using namespace std;
int mas[100][100];
int dx[8]={1,1,0,-1,-1,-1,0,1},dy[8]={0,1,1,1,0,-1,-1,-1};
int sx,sy,gx,gy,w,h,cnt=0;
void dfs(int x,int y);
int main(){
  while(1){
    cnt=0;
  cin >> w >> h;
  if(w==0 && h==0) break;
  for(int i=0;i<h;i++){
    for(int j=0;j<w;j++){
      cin >> mas[i][j];
    }
  }
  for(int i=0;i<h;i++){
    for(int j=0;j<w;j++){
      if(mas[i][j]==1){
        cnt++;
        dfs(j,i);
      }
    }
  }
  cout << cnt << endl;
  }
}
void dfs(int x,int y){
  mas[y][x]=0;
  for(int i=0;i<8;i++){
    int nx=x+dx[i];
    int ny=y+dy[i];
    if(nx >= 0&& nx < w && ny >= 0 && ny < h && mas[ny][nx]==1){
        dfs(nx,ny);
      }
  }
}

C++: #include<cstdio>
#include<cstdlib>
#include<ctime>
#include<cmath>
#include<cstring>
#include<cctype>
#include<complex>
#include<iostream>
#include<sstream>
#include<algorithm>
#include<functional>
#include<vector>
#include<string>
#include<stack>
#include<queue>
#include<map>
#include<set>
#include<bitset>
using namespace std;
 
const int dx[] = {1,1,0,-1,-1,-1,0,1};
const int dy[] = {0,1,1,1,0,-1,-1,-1};
#define INF 1e+8
#define EPS 1e-10
#define PB push_back
#define fi first
#define se second
#define ll long long 
#define reps(i,j,k) for(int i = (j); i < (k); i++)
#define rep(i,j) reps(i,0,j)
typedef pair<int,int> Pii;
typedef vector<int> vi;
void solve(int y,int x,int h,int w,int stage[52][52]){
    rep(i,8){
        int nx = x + dx[i];
        int ny = y + dy[i];
        if(nx < 0 || nx > w-1 || ny < 0 || ny > h-1 || stage[ny][nx] == 0)continue;
        stage[ny][nx] = 0;
        solve(ny,nx,h,w,stage);
    }
    return ;
}
int main(){
    int w,h;
    while(scanf("%d%d",&w,&h),w){
        int stage[52][52]={{0}};
        int ans = 0;
        rep(i,h){
            rep(j,w){
                scanf("%d",&stage[i][j]);
            }
        }
        rep(i,h){
            rep(j,w){
                if(stage[i][j] == 1){
                    stage[i][j] = 0;
                    solve(i,j,h,w,stage);
                    ans++;
                }
            }
        }
        printf("%d\n",ans);
    }
    return 0;
}

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

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

struct Data {
	int x, y, n;
};

int w, h;
int c[51][51];
stack<Data> st;

void land_dfs(int x, int y, int n) {
	

	c[x][y] = n;

	// 島の発見中
	// 周囲8マスに島チェック

	for (int yy = -1; yy <= 1; yy++) {
		for (int xx = -1; xx <= 1; xx++) {
			if (x + xx < 0 || x + xx >(w - 1)) continue;
			if (y + yy < 0 || y + yy >(h - 1)) continue;
			if (c[x + xx][y + yy] != 1) continue;

				st.push({ x + xx, y + yy, n });

		}
	}

}

int main() {

	while (true) {
		cin >> w >> h;
		if (w == 0 &&  h == 0) break;

		int count = 0;

		for (int y = 0; y < h; y++) {
			for (int x = 0; x < w; x++) {
				cin >> c[x][y];
			}
		}

		for (int y = 0; y < h; y++) {
			for (int x = 0; x < w; x++) {
				if (c[x][y] == 1) {
					count++;
					st.push({ x, y, count + 1 });


					while (!st.empty()) {
						const auto d = st.top();
						st.pop();
						land_dfs(d.x, d.y, d.n);
					}
				}
			}
		}

		cout << count << endl;
	}


	return 0;
}

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

using namespace std;

int dx[8] = {-1, -1, 0, 1, 1, 1, 0, -1};
int dy[8] = {0, 1, 1, 1, 0, -1, -1, -1};

void dfs(int x, int y, vector<vector<bool> >& Cango){
  
  Cango[x][y] = false;
  

  for(int i = 0; i < 8; i++){
    int nextx = x + dx[i];
    int nexty = y + dy[i];
    
    if(Cango[nextx][nexty]) dfs(nextx, nexty, Cango);

  }
}

int main(void)
{
  
  int w, h;
  int si, sj;
  while(1){
    cin >> w >> h;
    if(w == 0 && h == 0) break;

    vector<vector<bool> > Cango(h + 2, vector<bool>(w + 2, false));
    for(int i = 1 ; i <= h; i++){
      for(int j = 1; j <= w; j++){
	int input; cin >> input;
       Cango[i][j] = input;
      }
    }
    
    int counter = 0;

    for(int i = 1; i <= h; i++){
      for(int j = 1; j <= w; j++){
        if(Cango[i][j] == true){
          counter++;
           dfs(i, j, Cango);
         }
       }
     }
    cout << counter << endl;
  }

  return 0;
    
}