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>
using namespace std;

using i64 = long long int;

int c[51][51] = {0};

void bfs(int w, int h, int x, int y){
    if(x < 0 || x >= w)return;
    if(y < 0 || y >= h)return;
    if(c[y][x] == 0)return;

    c[y][x] = 0;
    for(int dy=-1;dy<=1;++dy){
        for(int dx=-1;dx<=1;++dx)
            bfs(w, h, x+dx, y+dy);
    }
}

int main(){
    int w, h;
    while(cin >> w >> h, w != 0){
        for(int i=0;i<h;++i){
            for(int j=0;j<w;++j)
                cin >> c[i][j];
        }

        int ans = 0;
        for(int i=0;i<h;++i){
            for(int j=0;j<w;++j){
                if(c[i][j] == 1){
                    bfs(w, h, j, i);
                    ans++;
                }
            }
        }

        cout << ans << endl;
    }

    return 0;
}

C++: #include <iostream>
#include <vector>
#include <algorithm>
#include <utility>
#include <queue>
#include <set>
#include <stdio.h>
#include <string>
using namespace std;
#define ll long long

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

void dfs(int h, int w) {
	field[h][w] = 0;

	for (int dx = -1; dx <= 1; dx++) {
		for (int dy = -1; dy <= 1; dy++) {
			int nh = h + dy;
			int nw = w + dx;

			if (nh < 0 || nw < 0 || nh >= H || nw >= W)continue;
			if (field[nh][nw] == 0)continue;

			dfs(nh, nw);
		}
	}
}

int main() {
	while (1) {
		cin >> W >> H;
		if (W == 0 && H == 0)break;
		field.assign(H, vector<int>(W, 0));
		for (int i = 0; i < H; i++) {
			for (int j = 0; j < W; j++) {
				cin >> field[i][j];
			}
		}
		int ans = 0;
		for (int i = 0; i < H; i++) {
			for (int j = 0; j < W; j++) {
				if (field[i][j] == 0)continue;
				dfs(i, j);
				ans++;
			}
		}
		cout << ans << endl;
	}
	return 0;
}

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

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

int H, W;
int sima[55][55];

bool seen[55][55];
void dfs(int h, int w){
  seen[h][w] = true;
  for(int dir=0; dir<8; dir++){
    int nh = h + dy[dir];
    int nw = w + dx[dir];
    if(nh>=H || nh<0 || nw>=W || nw<0){
      continue;
    }
    if(sima[nh][nw] == 0){
      continue;
    }
    if(seen[nh][nw]){
      continue;
    }
    dfs(nh, nw);
  }
}

int main(){
  while(1){
    cin >> W >> H;
    if(H == 0 && W == 0){
      break;
    }
    for(int h=0; h<H; h++){
      for(int w=0; w<W; w++){
        cin >> sima[h][w];
      }
    }
    memset(seen, 0, sizeof(seen));
    int count=0;
    for(int i=0; i<H; i++){
      for(int j=0; j<W; j++){
        if(seen[i][j]){
          continue;
        }
        if(sima[i][j] == 0){
          continue;
        }
        dfs(i, j);
        count++;
      }
    }
    cout << count << endl;
  }
  return 0;
}

C++: #include <iostream>
#include <vector>

std::vector<int> dx{1, 1, 0, -1, -1, -1, 0, 1};
std::vector<int> dy{0, 1, 1, 1, 0, -1, -1, -1};

void dfs(std::vector<std::vector<bool>> &seen, std::vector<std::vector<int>> &map, int x, int y){
//    std::cout << x << ", " << y << std::endl;
    seen.at(y).at(x) = true;
    for(int i = 0; i < 8; ++i){
        int nextX = x + dx.at(i), nextY = y + dy.at(i);
        if(!seen.at(nextY).at(nextX) && 1 == map.at(nextY).at(nextX)){
            dfs(seen, map, nextX, nextY);
        }
    }
}

int main(){
    int w, h;
    while(std::cin >> w >> h){
        if(0 == w && 0 == h){
            break;
        }

        std::vector<std::vector<int>> map(h + 2, std::vector<int>(w + 2, 0));
        for(int i = 1; i <= h; ++i){
            for(int j = 1; j <= w; ++j){
                std::cin >> map.at(i).at(j); 
            }
        }

        std::vector<std::vector<bool>> seen(h + 2, std::vector<bool>(w + 2, false));
        int count = 0;
        for(int i = 1; i <= h; ++i){
            for(int j = 1; j <= w; ++j){
                if(!seen.at(i).at(j) && 1 == map.at(i).at(j)){
                    dfs(seen, map, j, i);
                    ++count;
                } 
            }
        }
    
        std::cout << count << std::endl;
    }

    return 0;
}

C++: 
#include <stdio.h>
#include <stdlib.h>
#include <iostream>
#include <vector>
#include <string>
#include <queue>
#include <algorithm>
#include <math.h>
#include <utility>
#include <set>
#include <map>
#define INF 100000
#define rep(i,n) for(int i =0;i<n;i++)
using namespace std;
typedef long long int ll;

#define MAX 5000

int G[51][51];
int h,w;


void dfs(int x, int y){
    if(x<0||x>w||y<0||y>h) return;
    for (int i=-1; i<=1; i++) {
        for (int j=-1; j<=1; j++) {
            if (G[x+i][y+j]==1) {
                G[x+i][y+j]=0;
                dfs(x+i,y+j);
            }
        }
    }
}


int main(){
    for(;;){
        cin >> w >> h;
        if(w==0 and h == 0) break;
        int ans=0;
        for (int i=0; i<h; i++) {
            for (int j=0; j<w; j++) {
                G[i][j]=0;
            }
        }
        for (int i = 0; i<h;i++) {
            for (int j=0; j < w; j++) {
                cin >> G[i][j];
            }
        }
        for (int i=0; i<h; i++) {
            for (int j=0; j<w; j++) {
                if (G[i][j]==1) {
                    G[i][j]=0;
                    ans++;
                    dfs(i,j);
                }
            }
        }
        cout << ans <<endl;
    }
}