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>
using namespace std;

constexpr int MAX_H = 50;
constexpr int MAX_W = 50;

int H, W;
int grid[MAX_H][MAX_W];
bool reached[MAX_H][MAX_W];

#define OCTAS
#ifdef OCTAS
constexpr int dh[]{-1, -1, -1, 0, 0, +1, +1, +1};
constexpr int dw[]{-1, 0, +1, -1, +1, -1, 0, +1};
#else
constexpr int dh[]{-1, 0, 0, +1};
constexpr int dw[]{0, -1, +1, 0};
#endif

void dfs(int h, int w) {
  reached[h][w] = true;

  for (int i{}; i < sizeof(dh) / sizeof(int); ++i) {
    int nh = h + dh[i];
    if (nh < 0 || nh >= H)
      continue;
    int nw = w + dw[i];
    if (nw < 0 || nw >= W)
      continue;
    if (grid[nh][nw] == 0 || reached[nh][nw])
      continue;
    dfs(nh, nw);
  }
}

int main() {
  while (true) {
    cin >> H >> W;
    if (H == 0 && W == 0)
      break;
    for (int h{}; h < H; ++h) {
      for (int w{}; w < W; ++w) {
        reached[h][w] = false;
        cin >> grid[h][w];
      }
    }

    int island{};
    for (int h{}; h < H; ++h) {
      for (int w{}; w < W; ++w) {
        if (grid[h][w] == 0 || reached[h][w])
          continue;
        dfs(h, w);
        ++island;
      }
    }

    cout << island << endl;
  }

  return 0;
}

C++: #include <iostream>
#include <iomanip>
#include <string>
#include <vector>
#include <stack>
#include <queue>
#include <deque>
#include <set>
#include <map>
#include <utility>
#include <tuple>
#include <algorithm>
#include <cstdio>
#include <cmath>
#define rep(i, n) for(int i = 0; i < (n); i++)
using namespace std;
using ll = long long;
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return true; } return false; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return true; } return false; }

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

int w, h;
vector<vector<int>> grid;

void dfs(int x, int y) {
  grid[x][y] = 0;
  rep(i, 8) {
    if(x+dx[i] >= 0 && x+dx[i] < h && y+dy[i] >= 0 && y+dy[i] < w) {
      if(grid[x+dx[i]][y+dy[i]]) {
        dfs(x+dx[i], y+dy[i]);
      }
    }
  }
}

int main() {
  while(cin >> w >> h && (w || h)) {
    grid = vector<vector<int>>(h, vector<int>(w));
    rep(i, h) rep(j, w)
      cin >> grid[i][j];
    int ans = 0;
    rep(i, h) rep(j, w) {
      if(grid[i][j]) {
        ans++;
        dfs(i, j);
      }
    }
    cout << ans << endl;
  }
  return 0;
}

C++: #include<bits/stdc++.h>
#define rep(i,n) for(int i=0; i<n; i++)
using namespace std;
int table[105][105];
int check(int i, int j){
  for(int a=i-1; a<i+2; a++){
    for(int b=j-1; b<j+2; b++){
      if(table[a][b]==1){
        table[a][b]=0;
        check(a,b);
      }
    }
  }
  return 0;
}
int main(){
  int w,h;
  while(1){
    cin >> w >> h;
    if(w==0 && h==0) break;
    table[w+2][h+2]={};
    rep(i,h) rep(j,w) cin >> table[i+1][j+1];
    rep(i,h+1){
      rep(j,w+1){
        if(table[i][j]==1){
          table[i][j]=2;
          check(i,j);
        }
      }
    }
    int count=0;
    for(int i=1; i<h+1; i++) for(int j=1; j<w+1; j++) if(table[i][j]==2) count++;
    cout << count << endl;
  }
  return 0;
}

C++: #include<iostream>
#include<vector>
#include<stack>
#include<queue>
#include<utility>
using namespace std;
bool find1(vector< vector<int> >& C,vector< vector<int> >& check,int* findh,int* findw)
{
  for(int i = 0;i < C.size();++i)
    for(int j = 0;j < C[0].size();++j)
      if(C[i][j] == 1 && check[i][j] == 0){
	*findh = i;
	*findw = j;
	return true;
      }
  return false;
}
bool find2(vector< vector<int> >& C,vector< vector<int> >& check,int* findh,int* findw)
{
  if(C[*findh - 1][*findw - 1] == 1 && check[*findh - 1][*findw - 1] == 0){
    *findh -= 1;
    *findw -= 1;
    return true;
  }
  else if(C[*findh - 1][*findw] == 1 && check[*findh - 1][*findw] == 0){
    *findh -= 1;
    return true;
  }
  else if(C[*findh - 1][*findw + 1] && check[*findh - 1][*findw + 1] == 0){
    *findh -= 1;
    *findw += 1;
    return true;
  }
  else if(C[*findh][*findw - 1] == 1 && check[*findh][*findw - 1] == 0){
    *findw -= 1;
    return true;
  }
  else if(C[*findh][*findw + 1] == 1 && check[*findh][*findw + 1] == 0){
    *findw += 1;
    return true;
  }
  else if(C[*findh + 1][*findw - 1] == 1 && check[*findh + 1][*findw - 1] == 0){
    *findh += 1;
    *findw -= 1;
    return true;
  }
  else if(C[*findh + 1][*findw] == 1 && check[*findh + 1][*findw] == 0){
    *findh += 1;
    return true;
  }
  else if(C[*findh + 1][*findw + 1] == 1 && check[*findh + 1][*findw + 1] == 0){
    *findh += 1;
    *findw += 1;
    return true;
  }
  else return false;
}
int main()
{
  int w,h,findh,findw;
  stack< pair<int,int> > finish;
  queue<int> answer;
  while(cin >> h >> w && !(w == 0 && h == 0)){
    int howmany = 0;
    vector< vector<int> > C(h + 2,vector<int>(w + 2,0)),check(h + 2,vector<int>(w + 2,0)); 
    for(int i = 1;i <= h;++i)
      for(int j = 1;j <= w;++j)
	cin >> C[i][j];
    while(find1(C,check,&findh,&findw)){
      check[findh][findw] = 1;
      finish.push(make_pair(findh,findw));
      while(!finish.empty()){
	findh = finish.top().first;
	findw = finish.top().second;
	while(find2(C,check,&findh,&findw)){
	  finish.push(make_pair(findh,findw));
	  check[findh][findw] = 1;
	}
	finish.pop();
      }
      ++howmany;
    }
    answer.push(howmany);
  }
  for(;!answer.empty();answer.pop())
    cout << answer.front() << endl;
}