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>
#include <algorithm>
long long w, h;
std::vector<std::vector<int>> c;
void dfs(int x, int y){
    c[x][y] = 0;
    for(int i = -1; i <= 1; i++){
        for(int j = -1; j <= 1; j++){
            int newx = x + i, newy = y + j;
            if(0 <= newx && newx < h && 0 <= newy && newy < w && c[newx][newy] == 1) dfs(newx, newy);
        }
    }
}
int main(){
    while(1){
        w = 0;
        h = 0;
        std::cin >> w >> h;
        if(w == 0 && h == 0) break;
        std::vector<std::vector<int>> l;
        c = l;
        c.resize(h, std::vector<int> (w));
        for(int i =0 ; i < h; i++){
            for(int j = 0; j < w; j++) std::cin >> c[i][j];
        }
        long long ans = 0;
        for(int i = 0; i < h; i++){
            for(int j = 0; j < w; j++){
                if(c[i][j] == 1) {
                    dfs(i, j);
                    ans++;
                }
            }
        }
        std::cout << ans << std::endl;
    }
}

C++: #include <iostream>

using namespace std;

int W, H;
int field[55][55];

void input(void){
	cin >> W;
	cin >> H;

	for(int i = 0;i < H;i++){
		for(int j = 0;j < W;j++){
			cin >> field[j][i];
		}
	}
}

void dfs(int x, int y){
	field[x][y] = 0;

	for(int dx = -1;dx <= 1;dx++){
		for(int dy = -1;dy <= 1;dy++){
			int nx = x + dx, ny = y + dy;
			if(0 <= nx && nx < W && 0 <= ny && ny < H && field[nx][ny] == 1) dfs(nx, ny);
		}
	}

	return ;
}

int main(){
	while(1){
		int res = 0;
		input();
		if(W == 0 && H == 0) break;

		for(int i = 0;i < H;i++){
			for(int j = 0;j < W;j++){
				if(field[j][i] == 1){
					dfs(j, i);
					res++;
				}
			}
		}

		cout << res << endl;
	}

	return 0;
}

C++: #include <algorithm>
#include <cmath>
#include <climits>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <fstream>
#include <iostream>
#include <list>
#include <map>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <vector>
#include <cassert>

using namespace std;

#define LOG(...) printf(__VA_ARGS__)
//#define LOG(...)
#define FOR(i,a,b) for(int i=(int)(a);i<(int)(b);++i)
#define REP(i,n) for(int i=0;i<(int)(n);++i)
#define ALL(a) (a).begin(),(a).end()
#define RALL(a) (a).rbegin(),(a).rend()
#define EXIST(s,e) ((s).find(e)!=(s).end())
#define SORT(c) sort((c).begin(),(c).end())
#define RSORT(c) sort((c).rbegin(),(c).rend())
#define CLR(a) memset((a), 0 ,sizeof(a))

typedef long long ll;
typedef unsigned long long ull;
typedef vector<bool> vb;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef vector<vb> vvb;
typedef vector<vi> vvi;
typedef vector<vll> vvll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;

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

const int L_MAP = 50 + 2;
bool field[L_MAP][L_MAP];

const bool LAND = true;
const bool SEA = false;

void dfs(int x, int y){
    if(field[y][x] == SEA)
        return;

    field[y][x] = SEA;
    FOR(dy, -1, 1 + 1){
        FOR(dx, -1, 1 + 1){
            dfs(x+ dx, y + dy);
        }
    }
}

int main() {
    int w, h;
    while(cin >> w >> h, w|h){
        fill_n((bool *)field, L_MAP * L_MAP, SEA);
        REP(y, h){
            REP(x, w) {
                cin >> field[y + 1][x + 1];
            }
        }

        int cnt = 0;
        REP(y, h) {
            REP(x, w) {
                if (field[y + 1][x + 1] == LAND) {
                    dfs(x + 1, y + 1);
                    cnt ++;
                }
            }
        }

        cout << cnt << endl;
    }

}

C++: #include "bits/stdc++.h"
using namespace std;

int main() {
	int W, H;
	while (cin >> W >> H) {
		if (W == 0) return 0;
		vector<vector<int> > V(H, vector<int>(W));
		for (int i = 0; i < H; i++) {
			for (int j = 0; j < W; j++) cin >> V[i][j];
		}
		int ANS = 0;
		for (int i = 0; i < H; i++) {
			for (int j = 0; j < W; j++) {
				if (V[i][j] == 1) {
					ANS++;
					queue<pair<int, int> > Q;
					Q.push({ i, j });
					V[i][j] = 0;
					while (!Q.empty()) {
						pair<int, int> P = Q.front();
						Q.pop();
						for (int k = -1; k <= 1; k++) {
							for (int l = -1; l <= 1; l++) {
								int NX = P.first + k, NY = P.second + l;
								if (0 <= NX && NX < H && 0 <= NY && NY < W) {
									if (V[NX][NY] == 1) {
										V[NX][NY] = 0;
										Q.push({ NX, NY });
									}
								}
							}
						}
					}
				}
			}
		}
		cout << ANS << endl;
	}
}