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;

int dx8[8] = {1, 1, 0, -1, -1, -1, 0, 1};
int dy8[8] = {0, 1, 1, 1, 0, -1, -1, -1};

int w, h;

int field[51][51];
bool seem[51][51];

void dfs(int x, int y)
{
	field[y][x] = 0;
	for (int i = 0; i < 8; ++i)
	{
		int xx = x + dx8[i];
		int yy = y + dy8[i];

		if (xx < 0 || xx >= w || yy < 0 || yy >= h) continue;
		
		if (field[yy][xx] == 0) continue;

		dfs(xx, yy);
	}
}

int main(int argc, char **argv)
{
	while (true)
	{
		cin >> w >> h;
		if (w == 0 && h == 0) break;
		memset(field, 0, sizeof(field));
		for (int y = 0; y < h; ++y)
			for (int x = 0; x < w; ++x)
				cin >> field[y][x];

		int c{0};
		memset(seem, 0, sizeof(seem));
		for (int y = 0; y < h; ++y)
		{
			for (int x = 0; x < w; ++x)
			{
				if (field[y][x] == 0) continue;
				dfs(x, y);
				++c;
			}
		}
		std::cout << c << std::endl;
	}
}

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

int state[100][100];
bool reached[100][100];
int w,h;

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

void dfs(int x, int y) {

	if(x==0 || w<x || y==0 || h<y || state[x][y] == 0)
		return;
	if(reached[x][y] == true)
		return;

	reached[x][y]=true;

	for(int i=0; i<8; i++) {
		dfs(x+dx[i],y+dy[i]);
	}
}

int main() {

	memset(state, -1, sizeof(state));
	memset(reached, false, sizeof(reached));

	cin >> w >> h;
	for(int i=1; i<=w; i++) {
		for(int j=1; j<=h; j++) {
			cin >> state[i][j];
		}
	}
	int count=0;
	for(int i=1; i<=w; i++) {
		for(int j=1; j<=h; j++) {
			if(state[i][j]==0)
				continue;
			else{
				dfs(i,j);
				count++;
			}
		}
	}
	cout << count << endl;
	return 0;
}

C++: #include <cstdio>

using namespace std;

int w, h;
int field[50][51];

void dfs(int x, int y)
{
	field[x][y] = 0;
	
	for(int dx = -1; dx <= 1; dx++){
		for(int dy = -1; dy <= 1; dy++){
			int nx = x + dx;
			int ny = y + dy;
			
			if(0 <= nx && nx < h && 0 <= ny && ny < w && field[nx][ny] == 1) dfs(nx, ny);
		}
	}
	return ;
}

void solve(void){
	int res = 0;
	for(int i = 0; i < h; i++){
		for(int j = 0; j < w; j++){
			if(field[i][j] == 1){
				dfs(i, j);
				res++;
			}
		}
	}
	printf("%d\n", res);
}

int main(void)
{
	while(scanf("%d %d", &w, &h) != EOF){
		if(w == 0 && h == 0){ break; }
		for(int i = 0; i < h; i++){
			for(int j = 0; j < w; j++){
				scanf("%d", &field[i][j]);
			}
		}
		solve();
	}
	
	return 0;
}

C++: #include <iostream>
#include <math.h>
#include <algorithm>
#include <vector>
using std::cin;
using std::cout;
using std::endl;
using std::string;
using std::vector;
				
				
void del_island(int i,int j,vector<vector<int>> &v){	
	v[i][j] = 0;
	if(v[i-1][j] == 1){
		del_island(i-1,j,v);
	}
	
	if(v[i+1][j] == 1){
		del_island(i+1,j,v);
	}
	if(v[i][j-1] == 1){
		del_island(i,j-1,v);
	}
	
	if(v[i][j+1] == 1){
		del_island(i,j+1,v);
	}
	if(v[i-1][j-1] == 1){
		del_island(i-1,j-1,v);
	}
	
	if(v[i-1][j+1] == 1){
		del_island(i-1,j+1,v);
	}
	
	if(v[i+1][j-1] == 1){
		del_island(i+1,j-1,v);
	}
	
	if(v[i+1][j+1] == 1){
		del_island(i+1,j+1,v);
	}

}

void mapping(vector<vector<int>>v,int w,int h){
	for(int i = 1;i <= h ; i++){
		for(int j = 0; j <= w ;j++){
			cout << v[i][j];
		}
		cout <<endl;
	}
	cout << endl;
}
void mapping2(int i, int j){
	cout << "i = " << i << endl;
	cout << "j = " << j << endl;
}
int count_island(int w, int h,vector<vector<int>> v){
	int count = 0;
	for(int i = 1 ; i <= h ;i++){
		for(int j = 1 ;j <= w ;j++){
			//cout << v[i][j] ;
			if(v[i][j] == 1){
				count++;
				//cout << "hello" <<endl;
				del_island(i,j,v);
				//mapping2(i,j);
				
			}
		}
	}
	return count;
}
	
int main(){ 
	int w,h;
	vector<vector<int>> v(60,vector<int>(60,0));
	int count;

	while(1){
		cin >> w >> h;
		if(w == 0 && h == 0){
			break;
		}
		count = 0; 
		for(int i = 1; i <= 59 ; i++){
			for(int j = 1 ; j <= 59 ; j++){
				v[i][j] = 0;
			}
		}

		for(int i = 1;i <= h; i++){
			for(int j = 1; j <= w; j++){
				cin >> v[i][j];
			}
		}

		count = count_island(w,h,v);
		//mapping(v,50,50);


		cout << count << endl;
	}
}