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 <string>
#include <cstring>
#include <fstream>
#include <random>
#include <cmath>
#include <iomanip>
#include <climits>
#include <cstdlib>
#include <algorithm>
#include <vector>
#include <map>
#include <deque>
#include <map>
#include <set>
#include <queue>
#include <stack>
#include <list>
#include <unordered_map>
#include <bitset>
#include <sstream>
#include <new>
#include <typeinfo>
#include <iterator>

typedef long long ll;
typedef unsigned long long ull;
constexpr ll mop = 1000000007;
constexpr ll mop2 = 998244353;

using namespace std;

void dfs(const ll& x, const ll& y, vector<vector<bool>>& grid, const ll& h, const ll & w) {
	grid[x][y] = false;
	for (ll dx = -1; dx <= 1; dx++) {
		for (ll dy = -1; dy <= 1; dy++) {
			ll nextx = x + dx;
			ll nexty = y + dy;
			if (0 <= nextx && nextx < h && 0 <= nexty && nexty < w && grid[nextx][nexty] == true) {
				dfs(nextx, nexty, grid, h, w);
			}
		}
	}
}

int main() {
	while (true) {
		ll w, h;
		cin >> w >> h;
		if (w == 0 && h == 0) {
			break;
		}
		vector<vector<bool>> grid(h);
		for (ll i = 0; i < h; i++) {
			grid[i].resize(w);
			for (ll j = 0; j < w; j++) {
				ll tmp;
				cin >> tmp;
				grid[i][j] = (tmp == 1 ? true : false);
			}
		}
		ll ans = 0;
		for (ll i = 0; i < h; i++) {
			for (ll j = 0; j < w; j++) {
				if (grid[i][j] == true) {
					ans++;
					dfs(i, j, grid, h, w);
				}
			}
		}
		cout << ans << endl;
	}
}

C++: #include <iostream>
#include <string>
#include <utility>
#include <stack>
#include <vector>
#include <queue>
#include <algorithm>
#include <map>
#include <climits>
#include <set>
#include <numeric>
#include <iomanip>
#include <cmath>
#include <cstring>
using namespace std;
int grid[50][50];
bool used[50][50];
int move_h[8] = {-1, 1, 0, 0, -1, 1, -1, 1};
int move_w[8] = {0, 0, -1, 1, 1, -1, -1, 1};

void dfs(int cur_h, int cur_w, int h, int w){
  used[cur_h][cur_w] = true;
  for(int i = 0; i < 8; i++){
    int next_h = cur_h + move_h[i];
    int next_w = cur_w + move_w[i];

    if(0 <= next_h && next_h < h && 0 <= next_w && next_w < w 
        && !used[next_h][next_w] && grid[next_h][next_w] == 1){
      dfs(next_h, next_w, h, w);
    }
  }
}
int main(){
  while(true){
    int w;
    int h;
    cin >> w >> h;
    if(w == 0 && h == 0){
      break;
    }
    for(int i = 0; i < h; i++){
      for(int j = 0; j < w; j++){
        cin >> grid[i][j];
        used[i][j] = false;
      }
    }

    int ans = 0;
    for(int i = 0; i < h; i++){
      for(int j = 0; j < w; j++){
        if(!used[i][j] && grid[i][j] == 1){
          ans ++;
          dfs(i, j, h, w);
        }
      }
    }
    cout << ans << endl;
  }
  return 0;
}

C++: #include<iostream>
using namespace std;
void dfs(int,int);
int box[51][51];
int main(){
  int w,h,i,I,a;
  while(1){
    a=0;
    cin>>w>>h;
    if(w==0&&h==0) break;
    for(i=0;i<=h+1;i++){
      for(I=0;I<=w+1;I++){
	box[i][I]==0;
      }
    }
    for(i=1;i<=h;i++){
      for(I=1;I<=w;I++){
	cin>>box[i][I];
      }
    }
    for(i=1;i<=h;i++){
      for(I=1;I<=w;I++){
	if(box[i][I]==1){
	  dfs(i,I);
	  a++;
	}
      }
    }
    cout<<a<<endl;
  }
  return 0;
}
  void dfs(int i,int I){
  if(box[i][I]==0) return;
  box[i][I]=0;
  dfs(i,I+1);
  dfs(i+1,I+1);
  dfs(i+1,I);
  dfs(i+1,I-1);
  dfs(i,I-1);
  dfs(i-1,I-1);
  dfs(i-1,I);
  dfs(i-1,I+1);
  }

C++: #include<bits/stdc++.h>
using namespace std;

typedef long long ll;
typedef pair<int,int> P;

bool ok=true;
int c[60][60];
int w,h;
bool seen[60][60];
int dx[8]={1,-1,0,0,1,-1,1,-1};
int dy[8]={1,-1,1,-1,0,0,-1,1};

void dfs(int v,int u){
	if(!seen[v][u]){
		seen[v][u]=true;
		for(int i=0;i<8;i++){
			if(v+dx[i]>=0&&v+dx[i]<h&&u+dy[i]>=0&&u+dy[i]<w&&c[v+dx[i]][u+dy[i]]==1)dfs(v+dx[i],u+dy[i]);
		}
	}
	return;
}

int main(){
	while(ok){
		cin>>w>>h;
		if(w==0||h==0){
			ok=false;
			return 0;
		}
		for(int i=0;i<h;i++){
			for(int j=0;j<w;j++){
				cin>>c[i][j];
			}
		}
		for(int i=0;i<60;i++){
			for(int j=0;j<60;j++)seen[i][j]=false;
		}
		int ans=0;
		for(int i=0;i<h;i++){
			for(int j=0;j<w;j++){
				if(c[i][j]==1&&!seen[i][j]){
					ans++;
					dfs(i,j);
				}
			}
		}
		cout<<ans<<endl;
	}
	return 0;
}