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>
#include <string>
#include <cmath>
#include <algorithm>

using namespace std;

void er(int c[52][52],int i,int j){
    c[i][j]--;
    if(c[i+1][j-1])
        er(c,i+1,j-1);
    else if(c[i][j+1])
        er(c,i,j+1);
    else if(c[i+1][j])
        er(c,i+1,j);
    else if(c[i+1][j+1])
        er(c,i+1,j+1);
}

int main(void){
    int w,h;
    int i,j;
    int a;
    int c[52][52];
    while(true){
        cin >> w >> h;
        if(w == 0){
            break;
        }
        for(i = 0;i < 52;i++){
            for(j = 0;j < 52;j++){
                c[i][j] = 0;
            }
        }
        for(i = 1;i <= w;i++){
            for(j = 1;j <= h;j++){
                cin >> c[i][j];
            }
        }
        a = 0;
        for(i = 1;i <= w;i++){
            for(j = 1;j <= h;j++){
                if(c[i][j]){
                    er(c,i,j);
                    a++;
                }
            }
        }
        cout << a << endl;
    }
}

C++: // aribon2-2_f
#include <iostream>
#include <vector>

using namespace std;

#define REP(i, n) for (int (i) = 0 ; (i) < (int)(n) ; ++(i))
#define REPN(i, m, n) for (int (i) = m ; (i) < (int)(n) ; ++(i))
#define COUT(x) cout << x << endl

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

int W, H;
vector<vector<int>> C;

void dfs(int h, int w){
    C[h][w] = 0;
    REP(i, 8){
        int nh = h + dx[i];
        int nw = w + dy[i];
        if (C[nh][nw] == 0) continue;
        dfs(nh, nw);
    }
}

int main() {

    while (true){
        cin >> W >> H;
        if (W == 0 && H == 0) return 0;

        C.assign(H+2, vector<int>(W+2, 0));
        REP(i, H) REP(j, W){
            cin >> C[i+1][j+1];
        }

        int ans = 0;
        REPN(i, 1, H+1) REPN(j, 1, W+1){
            if (C[i][j] == 0) continue;
            dfs(i, j);
            ans++;
        }

        COUT(ans);
    }
}

C++: #include<bits/stdc++.h>

using namespace std;
using ll = long long;
using ld = long double;
#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define reps(i,s,n) for(int i=(int)(s);i<(int)(n);i++)
	int w, h;
	int c[50][50] = {};

	void dfs(int i, int j) {
		c[i][j] = 0;

		for (int di = -1; di <= 1;di++) {
			for (int dj = -1; dj <= 1;dj++) {
				int ni = i + di;
				int nj = j + dj;

				if (0 <= ni&&ni < h && 0 <= nj&&nj < w && c[ni][nj] == 1) {
					dfs(ni, nj); 
				}
			}
		}
		return;
}

int main() {
	cin.sync_with_stdio(false);
	vector<int>ans;
	while (1) {
		cin >> w >> h;
		rep(i, h) {
			rep(j, w) {
				cin >> c[i][j];
			}
		}
		int res = 0;
		rep(i, h) {
			rep(j, w) {
				if (c[i][j] == 1) {
					dfs(i, j);
					res++;
				}
			}
		}
		ans.push_back(res);

		if (w == 0&&h == 0) {
			break;
		}
	}
	rep(i, ans.size()) {
		cout << ans[i] << endl;
	}

	return 0;
}

C++: #include <iostream>
#include <vector>
#include <iomanip>
#include <cassert>
#include <cmath>
using namespace std; typedef long long ll; ll an=0; const ll INF = 1e18; const ll MOD = 1e9+7;
typedef pair<int,int> P;
vector<int> v[50];

void dfs(int x, int y, int r, int c) {
  if (!v[x][y]) return;
  //cout<<"("<<x<<","<<y<<","<<r<<","<<c<<") ";
  v[x][y] = 0;
  for(int p=-1;p<=1;p++) {
    for(int q=-1;q<=1;q++) {
      int f=x+p, g=y+q;
      if (0 <= f && f < c && 0 <= g && g < r && v[f][g]) {
        dfs(f,g,r,c);
      }
    }
  }
}
int main(){
  while(true) {
    int r,c; cin>>r>>c; if (r==0) return 0;
    for(int i=0;i<c;i++) {v[i].clear(); v[i].resize(r);}
    int an=0;
    for(int i=0;i<c;i++) {
      for(int j=0;j<r;j++) {
        int x; cin>>x; v[i][j]=x;
      }
    }
    for(int i=0;i<c;i++) {
      for(int j=0;j<r;j++) {
        if (v[i][j]) {an++, dfs(i,j,r,c);}
      }
    }
    cout<<an<<endl;
  }
}

C++: #include <iostream>
#include <vector>
using namespace std;

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

void dfs(vector< vector<int> > &plane, int x, int y){
  plane[x][y] = 0;
  for(int i=0; i<8; i++){
    if(0 <= x+dx[i] && x+dx[i] < h && 0 <= y+dy[i] && y+dy[i] < w)
      if(plane[x + dx[i]][y + dy[i]] == 1)
        dfs(plane, x + dx[i], y + dy[i]);
  }

  return;
}

int main(){
  while(true){
    cin >> w >> h;
    if(w == 0)
      break;

    vector< vector<int> > plane(h, vector<int>(w));
    for(int i=0; i<h; i++)
      for(int j=0; j< w; j++)
        cin >> plane[i][j];

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