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;

vector<vector<int>> m;
int xv[]={1,1,1,0,-1,-1,-1,0},yv[]={1,0,-1,-1,-1,0,1,1};


void bfs(int x,int y){
    stack<pair<int,int>> stk;
    m[x][y]=0;
    for(int i=0;i<8;i++){
        if(m[x+xv[i]][y+yv[i]]){
            stk.push(make_pair(x+xv[i],y+yv[i]));
        }
    }
    while(!stk.empty()){
        pair<int,int> tg=stk.top();
        stk.pop();
        bfs(tg.first,tg.second);
    }
    
}


void solve(int c,int r){
    int in,ans=0;
    m=vector<vector<int>>(r+2,vector<int>(c+2,0));
    for(int i=1;i<=r;i++){
        for(int j=1;j<=c;j++){
            cin>>in;
            m[i][j]=in;
        }
    }
    stack<pair<int,int>> stk;
    
    for(int i=1;i<=r;i++){
        for(int j=1;j<=c;j++){
            if(m[i][j]){
                ans++;
                bfs(i,j);
            }
        }
    }
    
    cout<<ans<<endl;
}

int main(void){
    int a,b;
    while(cin>>a>>b,a){
        solve(a,b);
    }
}

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

using namespace std;


int read_map(vector< vector <int> >& map,int &w, int &h){
  cin >> w >>  h;
  if (w == 0 && h == 0){
    return 0;
  }
  map.reserve(h);
  for (int i = 0; i < h ; ++i) map[i].resize(w);
  for (int i = 0; i < h; ++i)
  {
    for (int j = 0; j < w; ++j)
    {
      cin >> map[i][j];
    }
  }
  return 1;
}


bool island_check(vector<vector<int> >& map, int i, int j){
  if (map[i][j] == 1){
    return true;
  }
  return false;
}

void walk_island(vector<vector<int> >& map, int i, int j, int w, int h){
  int start_i, start_j;
  start_i = i;
  start_j = j;
  while (++j < w){
    if (island_check(map, i, j))
    {
      map[i][j] = 2;
    }else{
      break;
    }
  }
  j = start_j;
  while (--j >= 0){
    if (island_check(map, i, j))
    {
      map[i][j] = 2;
    }else{
      break;
    }
  }
  while (++i < h){
    if (island_check(map, i, j))
    {
      map[i][j] = 2;
    }else{
      break;
    }
  }
  i = start_i;
  while (--i >= 0){
    if (island_check(map, i, j))
    {
      map[i][j] = 2;
    }else{
      break;
    }
  }
  i = start_i;
  j = start_j;
  while (++i < h && ++j < w){
    if (island_check(map, i, j))
    {
      map[i][j] = 2;
    }else{
      break;
    }
  }
  i = start_i;
  j = start_j;
  while (--i >= 0 && ++j < w){
    if (island_check(map, i, j))
    {
      map[i][j] = 2;
    }else{
      break;
    }
  }
  i = start_i;
  j = start_j;
  while (--i >= 0 && --j >= 0){
    if (island_check(map, i, j))
    {
      map[i][j] = 2;
    }else{
      break;
    }
  }
  while (++i < h && --j >= 0){
    if (island_check(map, i, j))
    {
      map[i][j] = 2;
    }else{
      break;
    }
  }
}

int search_island_num(vector< vector <int> >& map, int w, int h){
  int island_count = 0;
  for (int i = 0; i < h; ++i)
  {
    for (int j = 0; j < w; ++j)
    {
      if(map[i][j] == 1){
        island_count++ ;
        map[i][j] = 2;
        walk_island(map, i, j, w, h);
      }
    }
  }
  return island_count;
}

int main(){
  vector< vector<int> > map;
  int w, h;
  while (read_map(map, w, h) != 0) {
    cout << search_island_num(map, w, h) << endl;
    map.clear();
  }
}

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

#define PIAR pair<int, int>

struct pos{
    int x;
    int y;
};

int main(){
    int w, h;
    while(cin >> w >> h, w != 0 && h != 0){
        int field[52][52] = {{0}};
        for(int i = 1; i <= h; i++){
            for(int j = 1; j <= w; j++){
                cin >> field[i][j];
            }
        }

        stack<PIAR> st;
        int island = 0;
        int dx[] = {-1,  0, 1, 0, -1,  1, 1, -1};
        int dy[] = {0 , -1, 0, 1, -1, -1, 1,  1};
        for(int i = 1; i <= h; i++){
            for(int j = 1; j <= w; j++){
                //島を探す
                if(field[i][j] == 1){
                    st.push(PIAR(j, i));
                    field[i][j] = 0;
                    while(!st.empty()){
                    	int x = st.top().first;
                    	int y = st.top().second;
                        st.pop();
                        for(int k = 0; k < 8; k++){
                            int nextX = x + dx[k];
                            int nextY = y + dy[k];
                            if(field[nextX][nextY] == 1){
                                st.push(PIAR(nextX, nextY));
                                field[nextX][nextY] = 0;
                            }
                        }
                    }
                    island++;
                }

            }
        }

        cout << island << endl;
    }
}

C++: #include <cstdio>

int w, h;
int data[64][64];
int movex[] = {-1, -1, -1, 0, 0, 1, 1, 1};
int movey[] = {-1, 0, 1, -1, 1, -1, 0, 1};

void dfs(int x, int y);

int main(void)
{	
	while (scanf("%d %d", &w, &h)){
		if (w == 0 && h == 0) break;
		
		for (int i = 0; i < 64; i++){
			for (int j = 0; j < 64; j++){
				data[i][j] = 0;
			}
		}
		
		for (int i = 1; i <= h; i++){
			for (int j = 1; j <= w; j++){
				scanf("%d", &data[i][j]);
			}
		}
		
		int res = 0;
		for (int i = 0; i < 64; i++){
			for (int j = 0; j < 64; j++){
				if (data[i][j] == 1){
					dfs(i, j);
					res++;
				}
			}
		}
		
		printf("%d\n", res);
	}
	
	return (0);
}

void dfs(int x, int y)
{
	data[x][y] = 0;
	
	for (int i = 0; i < 8; i++){
		if (data[x + movex[i]][y + movey[i]] == 1){
			dfs(x + movex[i], y + movey[i]);
		}
	}
	
	return;
}