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;

#define vec vector
#define rep(i, n) for (int i = 0; i < (int)n; i++)

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

int dp[55][55];
int c[55][55];

int check(int x, int y)
{
	if (dp[x][y]) return 0;
	if (c[x][y] == 0) return 0;
	dp[x][y] = 1;
	
	rep(i, 8) {
		int xx = x + dx[i];
		int yy = y + dy[i];
		int take = check(xx, yy);
	}
	return 1;
}

int main(void)
{
	while(1) {
		int w, h;
		cin >> w >> h;
		if (w == 0) break;
		rep(i, 55) rep(j, 55) c[i + 1][j + 1] = 0;
		rep(i, h) rep (j, w) cin >> c[i + 1][j + 1];
		rep(i, 55) rep(j, 55) dp[i][j] = 0;
		rep(i, 55) {
			dp[0][i] = 1;
			dp[i][0] = 1;
			dp[h + 1][i] = 1;
			dp[i][w + 1] = 1;
		}

		int ans = 0;
		rep(i, h) rep(j, w) if (c[i + 1][j + 1]) ans += check(i + 1, j + 1);
		cout << ans << endl;
	}
	return 0;
}

C++: #include <iostream>
#include <vector>
using namespace std;
int ans;
int w, h;
//?§???????
const int mx[] = {-1, 0, 1, -1, 1, -1, 0, 1 };
const int my[] = { 1, 1, 1, 0, 0, -1, -1, -1};
vector<int> vx;
vector<int> vy;

vector<vector<int>> area;
int islands = 0;

//????±????????????¨????????¢?´¢
void dfs(int i,int j){
	for (int n = 0; n < vx.size(); n++){
		int x = j + vx[n];
		int y = i + vy[n];
		if (x >= 0 && x < w &&
			y >= 0 && y < h &&
			area[y][x] == 1){
			area[y][x] = 2;
			dfs(y,x);
		}
	}
}

int main(){
	for (int i = 0; i < 8; i++){
		vx.push_back(mx[i]);
		vy.push_back(my[i]);
	}
	while (1){
		cin >> w >> h;
		if (w == 0 && h == 0) break;
		//?????????
		islands = 0;
		area.clear();
		area = vector<vector<int>>(h, vector<int>(w));
		//??\???
		for (int i = 0; i < h; i++){
			for (int j = 0; j < w; j++){
				cin >> area[i][j];
			}
		}
		//??¨??¢?´¢
		for (int i = 0; i < h; i++){
			for (int j = 0; j < w; j++){
				if (area[i][j] == 1){
					islands++;
					area[i][j] = 2;
					dfs(i, j);
				}
			}
		}
		cout << islands << endl;
	}
	return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define rep(i, n) for(ll i = 0; i < n; i++)
#define FOR(i, m, n) for(ll i = m; i < n; i++)
#define all(vec) vec.begin(), vec.end()
#define tmax(x, y, z) max((x), max((y), (z)))
#define tmin(x, y, z) min((x), min((y), (z)))
ll MM = 1000000000; ll mod = MM + 7; ll MMM=9223372036854775807;//2^63 -1
ll GCD(ll x, ll y){ if(y == 0) return x; else return GCD(y, x % y);}
ll LCM(ll x, ll y){ return x / GCD(x, y) * y;}
template<class T> inline bool chmin(T& a, T b){ if(a > b){ a = b; return true;} return false;}
template<class T> inline bool chmax(T& a, T b){ if(a < b){ a = b; return true;} return false;}
const ll INF = 1LL << 60;
using Graph = vector<vector<ll>>;
int dx[4] = {1, 0, -1, 0}, dy[4] = {0, 1, 0, -1};
int ddx[8] = {1, 1, 0, -1, -1, -1, 0, 1}, ddy[8] = {0, 1, 1, 1, 0, -1, -1, -1};
//cout << fixed << setprecision(10);

int field[100][100];
ll w, h;


void dfs(ll y, ll x){
    field[y][x] = 0;
    rep(i, 8){
        ll ny = y + ddy[i], nx = x + ddx[i];
        if(0 <= ny && ny < h && 0 <= nx && nx < w && field[ny][nx]){
            dfs(ny, nx);
        }
    }
}


int main(){
    vector<ll> res;
    while(1){
        cin >> w >> h;
        if(!w && !h) break;
        rep(hi, h){
            rep(wi, w){
                cin >> field[hi][wi];
            }
        }

        ll ans = 0;
        rep(hi, h){
            rep(wi, w){
                if(field[hi][wi]){
                    dfs(hi, wi);
                    ans++;
                }
            }
        }

        // cout << ans << endl;
        res.push_back(ans);
    }

    rep(i, res.size()) cout << res[i] << endl;
return 0;
}

C++: #include <algorithm>
#include <cstdio>
#include <iostream>
#include <map>
#include <cmath>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <vector>
#include <stdlib.h>
#include <stdio.h>
#include <cstring>
using namespace std;
#define FOR(I,A,B) for(int I = (A); I < (B); ++I)
#define CLR(mat) memset(mat, 0, sizeof(mat))
typedef long long ll;
int W, H;
int c[50][50];
bool visited[50][50];
int vy[8] = {-1,-1,0,1,1,1,0,-1};
int vx[8] = {0,1,1,1,0,-1,-1,-1};
void calc(int y, int x) {
  if(y < 0 || y >= H || x < 0 || x >= W) return;
  if(visited[y][x] || c[y][x] == 0) return;
  visited[y][x] = true;
  FOR(i,0,8) calc(y+vy[i],x+vx[i]);
  return;
}
int main()
{
  while(cin >> W >> H, (W || H)) {
    CLR(visited);
    FOR(y,0,H) FOR(x,0,W) cin >> c[y][x];
    int ans = 0;
    FOR(y,0,H) {
      FOR(x,0,W) {
        if(visited[y][x] || c[y][x] == 0) continue;
        calc(y, x);
        ans++;
      }
    }
    cout << ans << endl;
  }
  return 0;
}