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<stdio.h>
    //#include <bits/stdc++.h>
    #include<vector>
    #include<float.h>
    #include<iomanip>
    #include<algorithm>
    #include<string>
    #include<cstring>
    #include<math.h>
    #include<cmath>
    #include<sstream>
    #include<set>
    #include<map>
    #include<queue>
    #include<cassert>
    #include<cmath>
    #include<cstdint>
using namespace std;

bool seen[55][55];
vector<vector<int>> s(55, vector<int>(55));
int w, h;
void dfs(int y, int x){
    seen[y][x] = true;

    for(int i = -1; i <= 1; i++){
        for(int j = -1; j <= 1; j++){
            if(i == 0 && j == 0)continue;
            int ny = y + i, nx = x + j;
            
            if(ny < 0 || ny >= h || nx < 0 || nx >= w)continue;
            if(seen[ny][nx])continue;
            if(s[ny][nx] != 1)continue;
            dfs(ny, nx);
        }
    }
}
int main(){
    while(cin >> w >> h){
    if(w == 0 && h == 0)return 0;
    for(int i = 0; i < h; i++)for(int j = 0; j < w; j++){cin >> s[i][j];seen[i][j] = false;}
    int cnt = 0;
    for(int i = 0; i < h; i++){
        for(int j = 0; j < w; j++){
            if(seen[i][j])continue;
            if(s[i][j] == 0)continue;
            cnt++;
            dfs(i, j);
        }
    }
    cout << cnt << endl;
    }
}

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

using namespace std;

typedef long long ll;

template<class T>
inline bool chmax(T &a, T b) {
    if(a < b) {
        a = b;
        return true;
    }
    return false;
}

template<class T>
inline bool chmin(T &a, T b) {
    if(a > b) {
        a = b;
        return true;
    }
    return false;
}

void solve(int cur_x, int cur_y, vector<vector<bool>> &visited,
        const int H, const int W, const vector<vector<int>> &field) {
    visited[cur_y][cur_x] = true;

    vector<pair<int, int>> diff_xy = {
        {0, 1}, {1, 1}, {1, 0}, {1, -1}, {0, -1}, {-1, -1}, {-1, 0}, {-1, 1}
    };
    for (int i = 0; i < (int) diff_xy.size(); i++) {
        int next_x = cur_x + diff_xy[i].first;
        int next_y = cur_y + diff_xy[i].second;
        if (next_x < 0 || next_x >= W || next_y < 0 || next_y >= H) continue;
        if (visited[next_y][next_x]) continue;
        if (field[next_y][next_x] == 0) continue;
        solve(next_x, next_y, visited, H, W, field);
    }
}

int main(void) {
    while (1) {
        int w, h;
        cin >> w >> h;

        if (w == 0 && h == 0) break;

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

        vector<vector<bool>> visited(h, vector<bool>(w, false));
        int count = 0;
        for (int i = 0; i < h; i++) {
            for (int j = 0; j < w; j++) {
                if (visited[i][j]) continue;
                if (field[i][j] == 0) continue;
                solve(j, i, visited, h, w, field);
                count++;
            }
        }

        cout << count << endl;
    }
    return 0;
}

C++: #include <bits/stdc++.h>
#define REP(i, n) for(int i = 0; i < n; i++)
#define REPR(i, n) for(int i = n; i >= 0; i--)
#define FOR(i, m, n) for(int i = m; i < n; i++)
#define INF 2e9
#define ALL(v) (v).begin(), (v).end()
using namespace std;
typedef long long ll;
int GCD(int a,int b){return b?GCD(b,a%b):a;}
int LCM(int a,int b){return (a*b)/GCD(a,b);}
int abs(int x){return x>0?x:-x;}
 
const int dx[] = {1, 0, -1, 0, 1, -1, -1, 1};
const int dy[] = {0, 1, 0, -1, 1, 1, -1, -1};

int sea[50][50];
int w, h;
void dfs(int x, int y)
{
	sea[x][y] = 0;
	for (int i = 0; i < 8; i++){
		int nx = x + dx[i], ny = y + dy[i];
		if (0 <= nx and nx < h and 0 <= ny and ny < w and sea[nx][ny] == 1){
			dfs(nx, ny);
		}
	}

	return;
}

int main()
{
	while (1){
		int ans = 0;
		cin >> w >> h;
		if (!w and !h) return 0;
		REP(i, h){
			REP(j, w){
				cin >> sea[i][j];
			}
		}

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

		cout << ans << endl;
	}

}

C++: #include <cstdio>

int w, h, c[50][50], count = 0;

void search(int x, int y)
{
    c[y][x] = 0;

    for (int dx = -1; dx <= 1; ++dx)
    {
        for (int dy = -1; dy <= 1; ++dy)
        {
            if (x + dx < 0 || x + dx >= w || y + dy < 0 || y + dy >= h)
            {
                continue;
            }

            if (c[y + dy][x + dx] == 1)
            {
                search(x + dx, y + dy);
            }
        }
    }
}

bool sub_search()
{
    for (int i = 0; i < h; ++i)
    {
        for (int j = 0; j < w; ++j)
        {
            if (c[i][j] == 1)
            {
                search(j, i);
                count++;
                return true;
            }
        }
    }

    return false;
}

int main()
{
    while (true)
    {
        scanf("%d %d", &w, &h);
        if (w == 0 && h == 0)
        {
            break;
        }

        for (int i = 0; i < h; ++i)
        {
            for (int j = 0; j < w; ++j)
            {
                scanf("%d", &c[i][j]);
            }
        }

        count = 0;

        while (sub_search())
        {
        }

        printf("%d\n", count);
    }
}