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 <bits/stdc++.h>
using namespace std;

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

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

    for (int dh = -1; dh <= 1; ++dh) {
        for (int dw = -1; dw <= 1; ++dw) {
            int nh = h + dh, nw = w + dw;

            if(nh < 0 || nh  >= H || nw < 0 || nw >= W) continue;
            if(field[nh][nw] == 0) continue;

            dfs(nh, nw);
        }
    }
}

int main() {
    while (cin >> W >> H){
        if(H == 0 and 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];
            }
        }

        int count = 0;
        for (int h = 0; h < H; ++h) {
            for (int w = 0; w < W; ++w) {
                if(field[h][w] == 0) continue;
                dfs(h, w);
                count++;
            }
        }
        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<iomanip>
#include<algorithm>
#include<bitset>
#include<cctype>
#include<cmath>
#include<cstdio>
#include<cstring>
#include<functional>
#include<limits>
#include<list>
#include<map>
#include<set>
#include<stack>
#include<string>
#include<sstream>
#include<queue>
#include<vector>
using namespace std;

#define MOD 1000000007
#define INF 0x3f3f3f3f
#define INFL 0x3f3f3f3f3f3f3f3fLL

#define MAX 50
#define NIL -1

static char M[MAX][MAX];
static int color[MAX][MAX];
int W, H;

void dfs(int h, int w, int c) {
	color[h][w] = c;
	if (h != H - 1 && M[h + 1][w] == '1'&&color[h + 1][w] == NIL)
		dfs(h + 1, w, c);
	if (h != 0 && M[h - 1][w] == '1'&&color[h - 1][w] == NIL)
		dfs(h - 1, w, c);
	if (w != W - 1 && M[h][w + 1] == '1'&&color[h][w + 1] == NIL)
		dfs(h, w + 1, c);
	if (w != 0 && M[h][w - 1] == '1'&&color[h][w - 1] == NIL)
		dfs(h, w - 1, c);

	if (h != H - 1 && w != W - 1 && M[h + 1][w + 1] == '1'&&color[h + 1][w] == NIL)
		dfs(h + 1, w + 1, c);
	if (h != 0 && w != 0 && M[h - 1][w - 1] == '1'&&color[h - 1][w - 1] == NIL)
		dfs(h - 1, w - 1, c);
	if (h != 0 && w != W - 1 && M[h - 1][w + 1] == '1'&&color[h - 1][w + 1] == NIL)
		dfs(h - 1, w + 1, c);
	if (h != H - 1 && w != 0 && M[h + 1][w - 1] == '1'&&color[h + 1][w - 1] == NIL)
		dfs(h + 1, w - 1, c);
}


int main() {
	while (cin >> W >> H&&H&&W) {
		for (int h = 0; h < H; h++) {
			for (int w = 0; w < W; w++) {
				cin >> M[h][w];
			}
		}
		fill(color[0], color[MAX], NIL);
		int c = 0;
		for (int h = 0; h < H; h++) {
			for (int w = 0; w < W; w++) {
				if (color[h][w] == NIL&&M[h][w] == '1') { dfs(h, w, c++); }
			}
		}
		cout << c << endl;
	}
	return 0;
}

C++: //
//  main.cpp
//  ICPC2009B
//
//  Created by aki33524 on 2014/07/02.
//  Copyright (c) 2014年 aki33524. All rights reserved.
//

#include <iostream>
using namespace std;

int H, W;
int field[50][50];
int dh[] = {0, 0, 1, -1};
int dw[] = {1, -1, 0, 0};

void dfs(int h, int w){
    field[h][w] = 0;
    for(int i=-1; i<=1; i++){
        for(int j=-1; j<=1; j++){
            int nh = h + i;
            int nw = w + j;
            if(0<=nh&&nh<H && 0<=nw&&nw<W && field[nh][nw])
                dfs(nh, nw);
        }
    }
}

void solve(){
    int ans = 0;
    for(int h=0; h<H; h++){
        for(int w=0; w<W; w++){
            if(field[h][w]){
                dfs(h, w);
                ans++;
            }
        }
    }
    cout << ans << endl;
}

int main(int argc, const char * argv[])
{
    while(cin >> W >> H, H|W){
        for(int h=0; h<H; h++){
            for(int w=0; w<W; w++){
                cin >> field[h][w];
            }
        }
        solve();
    }
    
    return 0;
}