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;
using ll = long long;
using P = pair<int, int>;

int c[50][50];
void dfs(int i, int j, int w, int h) {
  c[i][j] = 0;
  rep(k, 3) {
    int di = i - 1 + k;
    if (di < 0 || h <= di) continue;
    rep(l, 3) {
      int dj = j - 1 + l;
      if (dj < 0 || w <= dj) continue;
      if (di == i && dj == j) continue;
      if (c[di][dj]) dfs(di, dj, w, h);
    }
  }
}

int main() {
  vector<int> ans;
  while (1) {
    int w, h;
    cin >> w >> h;
    if (w + h == 0) break;
    // vector<vector<int> > c(w, vector<int>(h));
    rep(i, h) rep(j, w) cin >> c[i][j];
    // cout << endl;
    // rep(i, h) {
    //   rep(j, w) printf("%d ", c[i][j]);
    //   cout << endl;
    // }
    int cnt = 0;
    rep(i, h) rep(j, w) {
      if (c[i][j] == 0) continue;
      cnt++;
      dfs(i, j, w, h);
      // rep(i, h) {
      //   rep(j, w) printf("%d ", c[i][j]);
      //   cout << endl;
      // }
    }
    ans.push_back(cnt);
  }
  for (int a : ans) cout << a << endl;
  return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
#define int long long
using ll=long long;
using vi=vector<int>;
using vl=vector<long long>;
using pii=pair<int,int>;
using pll=pair<long long,long long>;
#define ITR(i,c) for(auto i=begin(c);i!=end(c);++i)
#define FORE(x,c) for(auto &x:c)
#define REPF(i,a,n) for(int i=a,i##len=(int)(n);i<i##len;++i)
#define REP(i,n) REPF(i,0,n)
#define REPR(i,n) for(int i=(int)(n);i>=0;--i)
#define REPW(i,n) for(i=0;i<(int)(n);++i)
#define ALL(c) begin(c),end(c)
#define RALL(c) rbegin(c),rend(c)   // c++14
#define SZ(c) ((int)c.size())
#define EXIST(c,x) (c.find(x)!=end(c))
#define OUTOFRANGE(y,x,h,w) (y<0||x<0||y>=h||x>=w)
#define dump(...)
const int DX[9]={0,1,0,-1,1,1,-1,-1,0},DY[9]={-1,0,1,0,-1,1,1,-1,0};
#define INF (1001001001)
#define INFLL (1001001001001001001ll)
template<class T> ostream& operator << (ostream &os,const vector<T> &v) {
    ITR(i,v) os << *i << (i==end(v)-1 ? "" : " "); return os; }
template<class T> istream& operator >> (istream &is,vector<T> &v) {
    ITR(i,v) is >> * i; return is; }
template<class T> istream& operator >> (istream &is, pair<T,T> &p) {
        is >> p.first >> p.second; return is; }
template<class T>bool chmax(T &a,const T &b){if(a<b){a=b;return 1;}return 0;}
template<class T>bool chmin(T &a,const T &b){if(b<a){a=b;return 1;}return 0;}
//------------------------------------------------------------------------------
struct before_main_function {
    before_main_function() {
        #ifdef int
            #undef INF
            #define INF INFLL
            #define stoi stoll
        #endif
        cin.tie(0);ios::sync_with_stdio(false);
        cout<<setprecision(15)<<fixed;
    }
} before_main_function;
//------------------------------------------------------------------------------

void solve(int h,int w) {
    vector<vector<int>> c(h,vector<int>(w,0));
    cin>>c;
    int ans=0;
    REP(i,h) {
        REP(j,w) {
            if(c[i][j]) {
                queue<pii> q;
                q.push({i,j});
                while(!q.empty()) {
                    int y=q.front().first;
                    int x=q.front().second; q.pop();
                    REP(d,8) {
                        int yy=y+DY[d];
                        int xx=x+DX[d];
                        if(OUTOFRANGE(yy,xx,h,w)) continue;
                        if(!c[yy][xx]) continue;
                        q.push({yy,xx});
                        c[yy][xx]=0;
                    }
                }
                ans++;
            }
        }
    }
    cout<<ans<<endl;
}
signed main() {
    while(1) {
        int w,h;
        cin>>w>>h;
        if(w+h==0) break;
        solve(h,w);
    }
    return 0;
}

C++: #include<iostream>
using namespace std;
int map[114][514];
int h, w;
bool dfs(int i, int j) {
	map[i][j] = 0;
	if (i > 0) {
		if (j > 0) {
			if (map[i - 1][j - 1] == 1)dfs(i - 1, j - 1);
		}
		if(map[i - 1][j] = 1)dfs(i - 1, j);
		if (j < w) {
			if (map[i - 1][j + 1] == 1)dfs(i - 1, j + 1);
		}
	}
	if (j > 0) {
		if (map[i][j - 1] == 1)dfs(i, j - 1);
	}
	if (j < w) {
		if (map[i][j + 1] == 1)dfs(i, j + 1);
	}
	if (i < h) {
		if (j > 0) {
			if (map[i + 1][j - 1] == 1)dfs(i + 1, j - 1);
		}
		if (map[i + 1][j] = 1)dfs(i + 1, j);
		if (j < w) {
			if (map[i + 1][j + 1] == 1)dfs(i + 1, j + 1);
		}
	}
	return;
}
int main() {
	while (cin >> h >> w) {
		if (!h && !w)return 0;
		int INF = 0;
		for (int i = 0; i < h; i++)for (int j = 0; j < w; j++)cin >> map[i][j];
		for (int i = 0; i < h; i++)for (int j = 0; j < w; j++)if (map[i][j] == 1) {
			INF++;
			dfs(i, j);
		}
		cout << INF << endl;
	}
}