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>

#define rep(i, n) for(int i=0; i<n; i++)
using namespace std;


bool landfill(int x, int y, int w, int h, vector<vector<int> > &land) {
    if (x < 0 || y < 0 || x >= h || y >= w) return false;
    if (land.at(x).at(y) == 0) return false;
    land.at(x).at(y) = 0;
    return landfill(x, y + 1, w, h, land) || landfill(x, y - 1, w, h, land) ||
           landfill(x + 1, y, w, h, land) || landfill(x - 1, y, w, h, land) ||
           landfill(x - 1, y + 1, w, h, land) || landfill(x - 1, y - 1, w, h, land) ||
           landfill(x + 1, y + 1, w, h, land) || landfill(x + 1, y - 1, w, h, land);
}

int main() {
    vector<int> ans_union;
    do{
        int w, h;
        cin >> w >> h;
        if(w == 0 && h == 0) break;
        vector<vector<int> > land(h, vector<int>(w));

        int ans = 0;
        rep(i, h) rep(j, w) {
                cin >> land.at(i).at(j);
            }

        rep(i, h) rep(j, w) {
                if (land.at(i).at(j) == 1) {
                    ans++;
                    landfill(i, j, w, h, land);
                }
            }
        ans_union.push_back(ans);
    }while(1);
    for(int i = 0; i < ans_union.size(); i++){
        cout << ans_union.at(i) << endl;
    }

    return 0;

}

C++: #include <stdio.h>
#include <algorithm>
#include <vector>
#include <queue>
#include <memory.h>
#include <functional>

using namespace std;

//FILE * in = freopen("B", "r", stdin);

typedef pair<int,int> P;

int n, m;
int cnt = 0;
int data[100][100];
int check[100][100];

int mvx[] = {-1, 0, 1, -1, 1, -1, 0, 1};
int mvy[] = {-1, -1, -1, 0, 0, 1, 1, 1};

void input() {
	for(int i = 0; i < m; i++){
		for(int j = 0; j < n; j++) {
			scanf("%d", &data[i][j]);
		}
	}
	cnt = 0;
	memset(check, 0, sizeof(check));
}

void bfs(int x, int y) {
	queue<P> que;
	que.push(P(x,y));
	check[x][y] = 1;
	while(!que.empty()){
		P cur = que.front(); que.pop();
		for(int i = 0; i < 8; i++) {
			if(cur.first + mvx[i] >= 0 && cur.first + mvx[i] < m && cur.second + mvy[i] >= 0 && cur.second + mvy[i] < n
				&& data[cur.first + mvx[i]][cur.second + mvy[i]] && !check[cur.first+mvx[i]][cur.second+mvy[i]]){
					check[cur.first +mvx[i]][cur.second+mvy[i]] = 1;
					que.push(P(cur.first+mvx[i], cur.second+mvy[i]));
			}
		}
	}
}

void process() {
	for(int i = 0; i < m; i++) {
		for(int j = 0; j < n; j++) {
			if(data[i][j] && !check[i][j]) {
				bfs(i,j);
				++cnt;
			}
		}
	}
	printf("%d\n", cnt);
}

int main() {
	while(true) {
		scanf("%d%d", &n, &m);
		if(n == 0) break;
		input();
		process();
	}
	return 0;
}