Go: // AOJ 1160: How Many Islands? http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=1160

package main

import (
	"bufio"
	"container/list"
	"fmt"
	"os"
	"strconv"
)

var SEA = 0
var LAND = 1

func nextInt(sc *bufio.Scanner) int {
	sc.Scan()
	v, _ := strconv.Atoi(sc.Text())
	return v
}

func discoverIslands(M, V [][]int, H, W int) int {
	// 島を探す
	queue := list.New()
	islands := 0
	for i := 1; i <= H; i++ {
		for j := 1; j <= W; j++ {
			// 訪問済みの土地ならスキップ
			if V[i][j] == 1 {
				continue
			}

			// 訪問中の土地が海なら訪問済みにしてスキップ
			if M[i][j] == SEA {
				V[i][j] = 1
				continue
			}

			// 未訪問の陸地が見つかったので
			// 島の数を1つ増やし、この陸地から辿れる陸地を訪問していく
			islands++
			queue.PushBack([]int{i, j})

			for queue.Len() > 0 {
				cur := queue.Remove(queue.Front()).([]int)
				h, w := cur[0], cur[1]
				if V[h][w] == 1 {
					continue
				}
				V[h][w] = 1

				// 全方向に未訪問の陸地がないか探索
				for v := -1; v <= 1; v++ {
					for l := -1; l <= 1; l++ {
						dh := h + v
						dw := w + l
						if M[dh][dw] == LAND && V[dh][dw] == 0 {
							queue.PushBack([]int{dh, dw})
						}
					}
				}
				/*
					if M[h-1][w] == LAND {
						queue.PushBack([]int{h - 1, w})
					}
					if M[h-1][w+1] == LAND {
						queue.PushBack([]int{h - 1, w + 1})
					}
					if M[h][w+1] == LAND {
						queue.PushBack([]int{h, w + 1})
					}
					if M[h+1][w+1] == LAND {
						queue.PushBack([]int{h + 1, w + 1})
					}
					if M[h+1][w] == LAND {
						queue.PushBack([]int{h + 1, w})
					}
					if M[h+1][w-1] == LAND {
						queue.PushBack([]int{h + 1, w - 1})
					}
					if M[h][w-1] == LAND {
						queue.PushBack([]int{h, w - 1})
					}
					if M[h-1][w-1] == LAND {
						queue.PushBack([]int{h - 1, w - 1})
					}
				*/
			}
		}
	}
	return islands
}

func main() {
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)

	for {
		W, H := nextInt(sc), nextInt(sc)

		if W == 0 && H == 0 {
			break
		}
		// Initialize map and visted list
		M := make([][]int, H+2)
		V := make([][]int, H+2)
		for i := 0; i < H+2; i++ {
			M[i] = make([]int, W+2)
			V[i] = make([]int, W+2)
		}
		for i := 1; i <= H; i++ {
			for j := 1; j <= W; j++ {
				M[i][j] = nextInt(sc)
			}
		}

		islands := discoverIslands(M, V, H, W)

		fmt.Println(islands)
	}
}

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

int main() {
	int n;
	while (cin >> n, n) {

		vector<vector<int>>list(n, vector<int>(n, -1));
		int number;

		for (int i = 0;i < n;i++) {
			cin >> number;
			for (int j = 0;j < number;j++) {
				int codename;
				cin >> codename;
				list[i][codename - 1] = 1;
			}
		}//list[a][b]:a know b

		cin >> number;
		
		vector<int>ans(n,1);
		int leaked;
		for (int i = 0;i < number;i++) {
			cin >> leaked;
			for (int j = 0;j < n;j++) {
				if (list[j][leaked - 1] <= 0) ans[j] = 0;
			}
		}//who is imposible
		int sum = 0,telltale;

		for (int i = 0;i < n;i++) {
			sum += ans[i];
			if (ans[i] == 1) telltale = i + 1;
		}

		if (sum == 1)cout << telltale << endl;
		else cout << -1 << endl;

	}
	return 0;
}

C++: #include <sstream>
#include <string>
#include <vector>
#include <map>
#include <algorithm>
#include <iostream>
#include <utility>
#include <set>
#include <cctype>
#include <queue>
#include <stack>
#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <climits>
using namespace std;
#define INF 100000000
typedef long long ll;

int field[64][64];
bool done[64][64];
int w, h;

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

void dfs(int y, int x) {
    done[y][x] = true;
    for (int i = 0; i < 8; i++) {
        int ny = y + dy[i];
        int nx = x + dx[i];
        if (0 <= nx && nx < w && 0 <= ny && ny < h && field[ny][nx] == 1 && done[ny][nx] == false) {
            dfs(ny, nx);
        }
    }
}

int main(void) {
    while (1) {
        cin >> w >> h;
        if (w == 0 && h == 0) break;
        for (int i = 0; i < h; i++) {
            for (int j = 0; j < w; j++) {
                cin >> field[i][j];
                done[i][j] = false;
            }
        }
        int ans = 0;
        for (int i = 0; i < h; i++) {
            for (int j = 0; j < w; j++) {
                if (field[i][j] == 1 && done[i][j] == false) {
                    dfs(i, j);
                    ans++;
                }
            }
        }
        cout << ans << endl;
    }
    return 0;
}

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

using namespace std;

bool check(bool[50][50],pair<int, int>);
void rmv(bool[50][50], int, int);

int main(){
	for(int w, h; cin >> w >> h, w||h;){
		bool fld[50][50] = {0};
		int n;

		for(int i = 0; i < h; i++)
			for(int j = 0; j < w; j++)
				cin >> fld[i][j];

		for(n = 0; check(fld,make_pair(w, h)); n++);
		cout << n << endl;
	}
	return 0;
}


bool check(bool fld[50][50],pair<int, int> wide){
	for(int i = 0; i < wide.second; i++)
		for(int j = 0; j < wide.first; j++)
			if(fld[i][j]){
				rmv(fld, i, j);
				return true;
			}
	return false;
}

void rmv(bool fld[50][50], int y, int x){
	if(x >= 0 && y >= 0 && x <= 50 && y <= 50)
	if(fld[y][x]){
		fld[y][x] = false;
		for(int i = -1; i <= 1; i++)
			for(int j = -1; j <= 1; j++)
				rmv(fld, y+i , x+j);
	}
}

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

int w,h;
int mp[50][50];

void rec(int y,int x){
	if(mp[y][x]==0)return;
	mp[y][x]=0;
	if(x+1<w)rec(y,x+1);
	if(y+1<h)rec(y+1,x);
	if(x-1>=0)rec(y,x-1);
	if(y-1>=0)rec(y-1,x);
	if(x+1<w&&y-1>=0)rec(y-1,x+1);
	if(x+1<w&&y+1<h)rec(y+1,x+1);
	if(x-1>=0&&y+1<h)rec(y+1,x-1);
	if(y-1>=0&&x-1>=0)rec(y-1,x-1);
}

int main(){
	int x,y,ret;
	while(cin >> w >> h && w && h){
		ret = 0;
		for(int i=0;i<h;i++){
			for(int j=0;j<w;j++){
				cin >> mp[i][j];
			}
		}
		for(int i=0;i<h;i++){
			for(int j=0;j<w;j++){
				if(mp[i][j]){
					rec(i,j);
					ret++;
				}
			}
		}
		cout << ret << endl;
	}
	return 0;
}

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

using namespace std;
using ll = long long;

int w, h;
vector<vector<bool>> mp;


vector<pair<int,int>> dir{{0,1},{1,0},{-1,0},{0,-1},{1,1},{-1,-1},{1,-1},{-1,1}};

void dfs(int y, int x)
{
    for(auto i : dir){
        if(mp[y + i.first][x + i.second]){
            mp[y + i.first][x + i.second] = false;
            dfs(y + i.first, x + i.second);
        }
    }
}


int main()
{
    vector<int> AS;
    while(1){
        cin >> w >> h;
        if(!w && !h)break;
        mp.resize(h + 2,vector<bool>(w + 2));
        for(int i = 1; i <= h; i++){
            for(int j = 1; j <= w; j++){
                int t; cin >> t;
                mp[i][j] = t;
            }
        }

        int ans = 0;
        for(int i = 1; i <= h; i++){
            for(int j = 1; j <= w; j++){
                if(mp[i][j]){
                    mp[i][j] = false;
                    dfs(i, j);
                    ans++;
                }
            }
        }
        AS.push_back(ans);
    }
    for(auto i : AS)cout << i << endl;
}