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 INF_LL (int64)1e18
#define INF (int32)1e9
#define REP(i, n) for(int64 i = 0;i < (n);i++)
#define FOR(i, a, b) for(int64 i = (a);i < (b);i++)
#define all(x) x.begin(),x.end()
#define fs first
#define sc second

using int32 = int_fast32_t;
using uint32 = uint_fast32_t;
using int64 = int_fast64_t;
using uint64 = uint_fast64_t;
using PII = pair<int32, int32>;
using PLL = pair<int64, int64>;

const double eps = 1e-10;

template<typename A, typename B>inline void chmin(A &a, B b){if(a > b) a = b;}
template<typename A, typename B>inline void chmax(A &a, B b){if(a < b) a = b;}

class UnionFind{
private:
	vector<int32> par;
	int32 n;

public:
	UnionFind(){}
	UnionFind(int32 n):n(n){
		par.resize(n, -1);
	}

	int32 find(int32 x){
		return par[x] < 0 ? x : par[x] = find(par[x]);
	}

	int32 size(int32 x){
		return -par[find(x)];
	}

	void unite(int32 x, int32 y){
		x = find(x);
		y = find(y);
		if(x == y) return;
		if(size(x) < size(y)) swap(x, y);
		par[x] += par[y];
		par[y] = x;
	}

	bool same(int32 x, int32 y){
		return find(x) == find(y);
	}
};

int main(void){
	cin.tie(0);
	ios::sync_with_stdio(false);

	int32 w, h;
	while(cin >> w >> h && w && h){
		UnionFind uf((w+2)*(h+2));
		vector<vector<int32>> f(h+2, vector<int32>(w+2, '0'));
		REP(i, h){
			REP(j, w){
				cin >> f[i+1][j+1];
			}
		}
		int32 dx[] = {-1, -1, -1, 0, 0, 1, 1, 1};
		int32 dy[] = {-1, 0, 1, -1, 1, -1, 0, 1};
		FOR(y, 1, h+1){
			FOR(x, 1, w+1){
				REP(k, 8){
					int32 yy = y+dy[k], xx = x+dx[k];
					if(f[y][x] == 1 && f[yy][xx] == 1 && !uf.same(yy*(w+2)+xx, y*(w+2)+x)){
						uf.unite(yy*(w+2)+xx, y*(w+2)+x);
					}
				}
			}
		}
		int32 cnt = 0;
		REP(y, h+2){
			REP(x, w+2){
				if(f[y][x] == 1 && uf.find(y*(w+2)+x) == y*(w+2)+x)
					cnt++;
			}
		}
		cout << cnt << endl;
	}
}

C++: #include <bits/stdc++.h>
using namespace std;
 
int w=50,h=50;
vector<vector<int>>data(h,vector<int>(w));


void dfs(int x,int y){
	data[x][y]=0;
	for(int dx=-1;dx<=1;dx++){
    	for(int dy=-1;dy<=1;dy++){
        //四方の移動先を考え、陸を探す。
          int nx=x+dx, ny=y+dy;
        	if( 0<=nx && nx<h && 0<=ny && ny<w &&data[nx][ny]==1){
              dfs(nx,ny);
        	}
        }
    }     
}

int main() {
 while(1){w=0;h=0;
  cin >>w>>h;
  if(w==0&&h==0)return 0;
  for(int i=0;i<h;i++){
  	for(int j=0;j<w;j++){
    cin>>data.at(i).at(j);
    } 
  }
  
  int ans=0;
  for(int i=0;i<h;i++){
  	for(int j=0;j<w;j++){
   		if(data[i][j]==1){
        	dfs(i,j);
        	ans++;
        }
    } 
  }
 	cout <<ans <<endl; 
 }  
}

C++: #include<iostream>

using namespace std;

int h, w, map[51][51];

const int vx[] = {1,0,-1,0}, vy[] = {0,1,0,-1};

void island(int _w, int _h) {
	map[_w][_h] = 2;
	for (int i = 0;i < 4;i++) {
		if (_w + vy[i] >= 1 && _w + vy[i] <= w&&_h + vx[i] >= 1 && _h + vx[i] <= h&&map[_w+vy[i]][_h+vx[i]] == 1) {
			island(_w + vy[i], _h + vx[i]);
		}
	}
}

int main() {
	while (cin >> w >> h, w + h) {
		for (int i = 1;i <= w;i++) {
			for (int j = 1;j <= h;j++) {
				cin >> map[i][j];
			}
		}
		int count = 0;
		for (int i = 1;i <= w;i++) {
			for (int j = 1;j <= h;j++) {
				if (map[i][j] == 1) {
					count++, island(i, j);
				}
			}
		}
		cout << count << endl;
		for (int i = 1;i <= w;i++)for (int j = 1;j <= h;j++)map[i][j] = -1;
	}
	return 0;
}

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

int w, h;
int C[100][100];
bool R[100][100];

void dfs_visit(int h, int w, int y, int x){
    if(y < 0 || h <= y || x < 0 || w <= x || C[y][x] == 0){
        return;
    }
    
    if(R[y][x]){
        return;
    }
    
    R[y][x] = true;
    
    dfs_visit(h, w, y-1, x-1);
    dfs_visit(h, w, y-1, x);
    dfs_visit(h, w, y-1, x+1);
    dfs_visit(h, w, y, x-1);
    dfs_visit(h, w, y, x+1);
    dfs_visit(h, w, y+1, x-1);
    dfs_visit(h, w, y+1, x);
    dfs_visit(h, w, y+1, x+1);
}

int dfs(int h, int w){
    int cnt = 0;
    for(int i = 0; i < h; i++){
        for(int j = 0; j < w; j++){
            if(C[i][j] == 1 && !R[i][j]){
                cnt++;
                dfs_visit(h, w, i, j);
            }
        }
    }
    
    return cnt;
}


int main(void){

    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++){
                C[i][j] = 0;
                R[i][j] = false;
                cin >> C[i][j];
            }
        }
        
        cout << dfs(h, w) << endl;
    }
    
    return 0;

    
}