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 <stack>
using namespace std;
int dx[] = { -1, 0, 1, 1, 1, 0, -1, -1 };
int dy[] = { -1, -1, -1, 0, 1, 1, 1, 0 };

int main(){
	int w, h;
	while( cin >> w >> h && w && h ){
		int field[50][50];
		stack< pair<int, int> > st;
		for( int i = 0; i < h; i++ ){
			for( int j = 0; j < w; j++ ){
				cin >> field[i][j];
			}
		}
		int sum = 0;
		for( int i = 0; i < h; i++ ){
			for( int j = 0; j < w; j++ ){
				if( field[i][j] == 1 ){
					sum++;
					field[i][j] = 0;
					st.push( pair<int, int>(i, j) );
					//cout << i << ' ' << j << endl;
					while( !st.empty() ){
						//cout << st.top().second << ' ' << st.top().first << endl;
						int x0 = st.top().second;
						int y0 = st.top().first;
						st.pop();
						for( int k = 0; k < 8; k++ ){
							int x = x0 + dx[k];
							int y = y0 + dy[k];
							if( 0 <= x && x < w && 0 <= y && y < h && field[y][x] == 1 ){
								st.push( pair<int, int>(y, x) );
								field[y][x] = 0;
								//cout << y << ' ' << x << endl;
							}
						}
					}
				}
			}
		}
		cout << sum << endl;
	}
}

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 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] == 2) continue;
                else 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);
                        }else if(y-1 >= 0 && y-1 < h && x >= 0 && x < w && c[y-1][x] == 1){
                            que.push(y-1); que.push(x);
                        }else 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);
                        }else if(y >= 0 && y < h && x-1 >= 0 && x-1 < w && c[y][x-1] == 1){
                            que.push(y); que.push(x-1);
                        }else if(y >= 0 && y < h && x+1 >= 0 && x+1 < w && c[y][x+1] == 1){
                            que.push(y); que.push(x+1);
                        }else 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);
                        }else if(y+1 >= 0 && y+1 < h && x >= 0 && x < w && c[y+1][x] == 1){
                            que.push(y+1); que.push(x);
                        }else 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);
                        }
                    }
                    ans++;
                }
            }
        }

        cout << ans << endl;
    }
}

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

void input(int **, int, int);
int howManyIslands(int **, int, int);
void howBigIslands(int **, bool **, int, int, int, int);

int main()
{
	int **island, w, h;
	while(true){
		cin >> w >> h;
		if(w==h && h==0) break;
		island = new int*[w];
		for(int i=0; i<w; i++)
			island[i] = new int[h];
		input(island, w, h);
		cout << howManyIslands(island, w, h) << endl;
		for(int i=0; i<w; i++)
			delete[] island[i];
		delete[] island;
	}
	return 0;
}

void input(int **island, int w, int h)
{
	char *buf;
	cin.clear();cin.ignore();
	for(int i=0; i<h; i++){
		buf = new char[w*2];
		cin.getline(buf, sizeof(buf));
		int j=0, k=0;
		while(buf[j] != '\0'){
			if(buf[j] != ' '){
				switch(buf[j]){
				case '0':
					island[k][i] = 0;
					k++;
					break;
				case '1':
					island[k][i] = 1;
					k++;
					break;
				}
				if(w==k) break;
			}
			j++;
		}
		delete[] buf;
	}
}

int howManyIslands(int **island, int w, int h)
{
	bool **check;
	int ans = 0;
	check = new bool*[w];
	for(int i=0; i<w; i++){
		check[i] = new bool[h];
		for(int j=0; j<h; j++)
			check[i][j] = false;
	}

	for(int i=0; i<w; i++){
		for(int j=0; j<h; j++)
			cout<<check[i][j];
		cout<<endl;
	}


	for(int i=0; i<w; i++){
		for(int j=0; j<h; j++){
			if(check[i][j])continue;
			if(island[i][j]){
				ans++;
				howBigIslands(island, check, i, j, w, h);
			} else {
				check[i][j] = true;
			}
		}
	}
	for(int i=0; i<w; i++)
		delete[] check[i];
	delete[] check;

	return ans;
}

void howBigIslands(int **island, bool **check, int x, int y, int w, int h)
{
	cout<<"check"<<endl;
	for(int i=0; i<w; i++){
		for(int j=0; j<h; j++)
			cout<<check[i][j];
		cout<<endl;
	}
	cout<<endl<<"island"<<endl;
	for(int i=0; i<w; i++){
		for(int j=0; j<h; j++)
			cout<<island[i][j];
		cout<<endl;
	}
	cout<<endl<<endl;
	if(check[x][y]) return;
	enum __DIR{ UPPER_LEFT, UP, UPPER_RIGHT, LEFT, RIGHT, LOWER_LEFT,
		UNDER, LOWER_RIGHT, DIR_END};
	int periphe[DIR_END][2]={
			{-1, -1}, {0, -1}, {1, -1},
			{-1, 0}, {1, 0},
			{-1, 1}, {0, 1}, {1, 1}
	};
	check[x][y] = true;
	for(int i=0; i<DIR_END; i++){
		int newx = x+periphe[i][0],
			newy = y+periphe[i][1];
		if(newx < 0 || w-1 < newx ||
			newy < 0 || h-1 < newy) continue;
		if(island[newx][newy]){
			if(!check[newx][newy])
				howBigIslands(island, check,
				newx, newy, w, h);
		}
	}
}