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>
#include <string>
#include <vector>
#define rep(i,n) for (int i = 0;i < (n); ++i)
using namespace std;
using ll = long long;
using P = pair<int,int>;


//AOJ How many islands?
//http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=1160&lang=jp

int dx[8] = {1,-1,0,0,1,1,-1,-1};
int dy[8] = {0,0,1,-1,1,-1,1,-1};
int h,w;
using Graph = vector<vector<int>>;
vector<vector<bool>> seen;
vector<vector<int>> maze;

void dfs(P p){
    seen[p.first][p.second] = true;

    for(int i = 0;i < 8;i++){
        int nx = p.second + dx[i];
        int ny = p.first + dy[i];
        if(nx < 0 || ny < 0 || h <= ny || w <= nx) continue;
        if(seen[ny][nx]) continue;
        if(maze[ny][nx] == 0) continue;

        dfs(make_pair(ny,nx));
    }
}

void recur(int w,int h) {
    int count = 0;
    maze.assign(h,vector<int>(w,0));
    seen.assign(h,vector<bool>(w,false));
    for(int i = 0;i < h;i++){
        for(int j = 0;j < w;j++){
            cin >> maze[i][j];
        }
    }

    for(int i = 0;i < h;i++){
        for(int j = 0;j < w;j++){
            if(maze[i][j]==0) continue;
            if(seen[i][j]) continue;
            dfs(make_pair(i,j));
            count++;
        }
    }
    
    cout << count << endl;
    w = 0;
    h = 0;
}

int main(){
    while(true){
        cin >> w >> h;
        if(w*w + h*h == 0) break;
        recur(w,h);
    }
    return 0;
}



// #include <bits/stdc++.h>
// #include <string>
// #include <vector>
// #define rep(i,n) for (int i = 0;i < (n); ++i)
// using namespace std;
// using ll = long long;
// using P = pair<int,int>;


// //AOJ How many islands?
// //http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=1160&lang=jp

// int dx[8] = {1,-1,0,0,1,1,-1,-1};
// int dy[8] = {0,0,1,-1,1,-1,1,-1};
// int h,w;
// using Graph = vector<vector<int>>;
// vector<vector<bool>> seen;
// vector<vector<int>> maze;

// void dfs(P p){
//     seen[p.first][p.second] = true;

//     for(int i = 0;i < 8;i++){
//         int nx = p.second + dx[i];
//         int ny = p.first + dy[i];
//         if(nx < 0 || ny < 0 || h <= ny || w <= nx) continue;
//         if(seen[ny][nx]) continue;
//         if(maze[ny][nx] == 0) continue;

//         dfs(make_pair(ny,nx));
//     }
// }

// int main() {
//     cin >> w >> h;
//     int count = 0;
//     maze.assign(h,vector<int>(w,0));
//     seen.assign(h,vector<bool>(w,false));
//     for(int i = 0;i < h;i++){
//         for(int j = 0;j < w;j++){
//             cin >> maze[i][j];
//         }
//     }

//     for(int i = 0;i < h;i++){
//         for(int j = 0;j < w;j++){
//             if(maze[i][j]==0) continue;
//             if(seen[i][j]) continue;
//             dfs(make_pair(i,j));
//             count++;
//         }
//     }
    
//     cout << count << endl;
// }

C++: #include <bits/stdc++.h>
#define rep(i,a,b) for (int64_t i = (a); i < (b); i++)
#define REP(i,n) rep(i,0,n)
#define ALL(a) begin(a),end(a)
#define sz(s) (s).size()
#define pb push_back
#define mp make_pair
#define fi first
#define se second
using namespace std;
typedef long long ll;
int dx[]={1,-1,0,0,1,-1,1,-1};
int dy[]={0,0,1,-1,1,-1,-1,1};

int w,h,ans=0;
bool c[55][55];

void bfs(int y,int x)
{
    c[y][x]=0;
    REP(i,8) 
    {
        int ny=y+dy[i];int nx=x+dx[i];
        if(c[ny][nx]&&ny>=0&&ny<h&&nx>=0&&nx<w)bfs(ny,nx);
    }
}

int main()
{

    while(cin>>w>>h,w>0)
    {
        REP(i,h)REP(j,w)cin>>c[i][j];
        ans=0;c[55][55]={};
        REP(i,h)REP(j,w)if(c[i][j]){bfs(i,j);ans++;}
        cout<<ans<<endl;
    }
}

C++: #include <bits/stdc++.h>
using namespace std;
const int size = 12;
//const int size = 14;
char a[size][size];
int cnt = 0;
void dfs(int x, int y){
    //現在地を０にする
    a[x][y] = 0;
    //4近傍を探索
    //x+1, y
    int nx = x+1, ny=y;
    if(0 <= nx and nx < 12 and 0 <= ny and ny < 12 and a[nx][ny] == '1') dfs(nx, ny);
    //x-1, y
    nx = x-1, ny = y;
    if(0 <= nx and nx < 12 and 0 <= ny and ny < 12 and a[nx][ny] == '1') dfs(nx, ny);
    //x, y+1
    nx = x, ny = y+1;
    if(0 <= nx and nx < 12 and 0 <= ny and ny < 12 and a[nx][ny] == '1') dfs(nx, ny);
    //x, y-1
    nx = x, ny = y - 1;
    if(0 <= nx and nx < 12 and 0 <= ny and ny < 12 and a[nx][ny] == '1') dfs(nx, ny);
    return;
}

int main(){
    while (1) {
    cnt = 0;
    //マップを入力
    for(int i=0; i < 12; i++){
        for(int j=0; j < 12; j++) if(!(cin >> a[i][j])) return 0;
    }


    //サーチ
    for(int i=0; i < 12; i++){
        for(int j=0; j < 12; j++){
            if(a[i][j] == '1'){
                cnt += 1;
                dfs(i, j);
            }
        }
    }

    cout << cnt << endl;
}
    return 0;
}