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 <math.h>
#include <algorithm>
#include <vector>
using std::cin;
using std::cout;
using std::endl;
using std::string;
using std::vector;
				
				
vector<vector<int>> del_island(int i,int j,vector<vector<int>> v){	
	v[i][j] = 0;
	vector<vector<int>> answer = v;
	if(v[i-1][j] == 1){
		answer = del_island(i-1,j,answer);
	}
	if(v[i+1][j] == 1){
		answer = del_island(i+1,j,answer);
	}
	if(v[i][j-1] == 1){
		answer = del_island(i,j-1,answer);
	}
	if(v[i][j+1] == 1){
		answer = del_island(i,j+1,answer);
	}
	if(v[i-1][j-1] == 1){
		answer = del_island(i-1,j-1,answer);
	}
	if(v[i-1][j+1] == 1){
		answer = del_island(i-1,j+1,answer);
	}
	if(v[i+1][j-1] == 1){
		answer = del_island(i+1,j-1,answer);
	}
	if(v[i+1][j+1] == 1){
		answer = del_island(i+1,j+1,answer);
	}
	return answer;
}


int count_island(int w, int h,vector<vector<int>> v){
	int count = 0;
	for(int i = 1 ; i <= h ;i++){
		for(int j = 1 ;j <= w ;j++){
			//cout << v[i][j] ;
			if(v[i][j] == 1){
				count++;
				//cout << "hello" <<endl;
				v = del_island(i,j,v);
			}
		}
	}
	return count;
}
	
int main(){ 
	int w,h;
	vector<vector<int>> v(60,vector<int>(60,0));
	int count;

	while(1){
		cin >> w >> h;
		if(w == 0 && h == 0){
			break;
		}
		count = 0; 

		for(int i = 1;i <= h; i++){
			for(int j = 1; j <= w; j++){
				cin >> v[i][j];
			}
		}

		count = count_island(w,h,v);


		cout << count << endl;
	}
}

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

// 入力
int H, W;
vector<vector<int>> field;

// 探索
void dfs(int h, int w) {
    field[h][w] = 0;

    // 八方向を探索
    for (int dh = -1; dh <= 1; ++dh) {
        for (int dw = -1; dw <= 1; ++dw) {
            int nh = h + dh, nw = w + dw;

            // 場外アウトしたり、0 だったりはスルー
            if (nh < 0 || nh >= H || nw < 0 || nw >= W) continue;
            if (field[nh][nw] == 0) continue;

            // 再帰的に探索
            dfs(nh, nw);
        }
    }
}

int main() {
    // 入力受け取り
    while (cin >> W >> H) {
        if (H == 0 || W == 0) break;
        field.assign(H, vector<int>(W, 0));
        for (int h = 0; h < H; ++h) for (int w = 0; w < W; ++w) cin >> field[h][w];

        // 探索開始
        int count = 0;
        for (int h = 0; h < H; ++h) {
            for (int w = 0; w < W; ++w) {
                if (field[h][w] == 0) continue; // 残島じゃなかったらスルー
                dfs(h, w);
                ++count;
            }
        }
        cout << count << endl;
    }
}

C++: #include <iostream>
#include <queue>
#include <utility>

using namespace std;

using Point = pair<int,int>;

int map[52][52];

void BFS(const Point &p0){
  queue<Point> q;
  q.push(p0);
  while(!q.empty()){
    auto p = q.front();q.pop();
    int y = p.first , x = p.second;
    map[y][x] = 0;

    for(int i=-1;i<=1;++i){
      for(int j=-1;j<=1;++j){
        if(map[i+y][j+x]){
          q.push(Point(i+y,j+x));
        }
      }
    }
  }

}

int main(){
  int w,h;
  while(cin >> w >> h&&w>0&&h>0){
    for(int i=1;i<h+1;++i){
      for(int j=1;j<w+1;++j){
        cin >> map[i][j];
      }
    }

    int num = 0;
    for(int i=1;i<h+1;++i){
      for(int j=1;j<w+1;++j){
        if(map[i][j]){
          BFS(Point(i,j));
          num++;
        }
      }
    }
    cout << num << endl;
  }

  return 0;
}

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] <= h&&_h + vx[i] >= 1 && _h + vx[i] <= w&&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 <= h;i++) {
			for (int j = 1;j <= w;j++) {
				cin >> map[i][j];
			}
		}
		int count = 0;
		for (int i = 1;i <= h;i++) {
			for (int j = 1;j <= w;j++) {
				if (map[i][j] == 1) {
					count++, island(i, j);
				}
			}
		}
		cout << count << endl;
		for (int i = 1;i <= 50;i++)for (int j = 1;j <= 50;j++)map[i][j] = -1;
	}
	return 0;
}

C++: #include<iostream>
#include<math.h>
#include<stdlib.h>
#include<string>
#include<limits.h>
#include<vector>
using namespace std;
typedef long long ll;
bool search(int i, int j, vector<vector<int>>& c, vector<vector<bool>> &gone) {
	if (gone[i][j])return false;
	if (c[i][j] == 0)return false;
	gone[i][j] = true;
	for (int I = -1; I < 2; I++) {
		for (int J = -1; J < 2; J++) {
			if(i+I>=0&&j+J>=0&&i+I<c.size()&&j+J<c[0].size())
			search(i + I, j + J, c, gone);
		}
	}
	return true;
}
int main() {
	int w, h;
	while (true) {
		cin >> w >> h;
		if (w == 0 && h == 0) {
			return 0;
		}
		vector<vector<int>> c(h, vector<int>(w, 0));
		for (int i = 0; i < h; i++) {
			for (int j = 0; j < w; j++) {
				cin >> c[i][j];
				//cout << c[i][j] << " ";
			}
			//cout << endl;
		}
		vector<vector<bool>> gone(h, vector<bool>(w, false));
		int ans=0;
		for (int i = 0; i < h; i++) {
			for (int j = 0; j < w; j++) {
				if (search(i, j, c, gone)) {
					ans++;
				}
			}
		}
		cout << ans << endl;
	}
}