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;

const long long mod = 1e9 + 7;

using ll = long long;
using pii  = pair<int, int>;
using pll = pair<ll, ll>;
#define ull unsigned long long
#define ld long double
#define vi vector<int>
#define vll vector<ll>
#define vc vector<char>
#define vs vector<string>
#define vpii vector<pii>
#define vpll vector<pll>

#define rep(i, n) for (int i = 0, i##_len = (n); i < i##_len; i++)
#define rep1(i, n) for (int i = 1, i##_len = (n); i <= i##_len; i++)
#define repr(i, n) for (int i = ((int)(n)-1); i >= 0; i--)
#define rep1r(i, n) for (int i = ((int)(n)); i >= 1; i--)

#define sz(x) ((int)(x).size())
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()

#define SORT(v, n) sort(v, v + n);
#define VSORT(v) sort(v.begin(), v.end());
#define RSORT(x) sort(rall(x));
#define pb push_back
#define mp make_pair

#define INF (1e9)
#define PI (acos(-1))
#define EPS (1e-7)

ull gcd(ull a, ull b) { return b ? gcd(b, a % b) : a; }
ull lcm(ull a, ull b) { return a / gcd(a, b) * b; }

int w, h;
vector<vi> c, ids;
const vi dj = { -1, 0, 1, -1, 1, -1, 0, 1 }, di = { -1, -1, -1, 0, 0, 1, 1, 1 };
void dfs(int i, int j, int id) {
    ids[i][j] = id;
    rep(k, 8) {
        int ni = i + di[k], nj = j + dj[k];
        if (ni<0 || ni>=h || nj<0 || nj>=w) continue;
        if (c[ni][nj]==0 || ids[ni][nj]==id) continue;
        dfs(ni, nj, id);
    }
}

int main(){
    while (1) {
        cin >> w >> h;
        if (w==0 && h==0) break;
        c = vector<vi>(h, vi(w));
        rep(i, h) rep(j, w) cin >> c[i][j];
        ids = vector<vi>(h, vi(w, -1));
        int ans = 0;
        rep(i, h) rep(j, w) {
            if (c[i][j]==0 || ids[i][j]!=-1) continue;
            dfs(i, j, ans);
            ++ans;
        }
        cout << ans << endl;
    }
    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;
				
				
vector<vector<int>> del_island(int i,int j,vector<vector<int>> v){	
	v[i][j] = 0;
	vector<vector<int>> answer = v;
	if(v[i-1][j] == 1){
		answer = del_island(i-1,j,answer);
	}
	if(v[i+1][j] == 1){
		answer = del_island(i+1,j,answer);
	}
	if(v[i][j-1] == 1){
		answer = del_island(i,j-1,answer);
	}
	if(v[i][j+1] == 1){
		answer = del_island(i,j+1,answer);
	}
	if(v[i-1][j-1] == 1){
		answer = del_island(i-1,j-1,answer);
	}
	if(v[i-1][j+1] == 1){
		answer = del_island(i-1,j+1,answer);
	}
	if(v[i+1][j-1] == 1){
		answer = del_island(i+1,j-1,answer);
	}
	if(v[i+1][j+1] == 1){
		answer = del_island(i+1,j+1,answer);
	}
	return answer;
}


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

		count = count_island(w,h,v);


		cout << count << endl;
	}
}

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

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

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

    // 八方向を探索
    for (int dh = -1; dh <= 1; ++dh) {
        for (int dw = -1; dw <= 1; ++dw) {
            int nh = h + dh, nw = w + dw;

            // 場外アウトしたり、0 だったりはスルー
            if (nh < 0 || nh >= H || nw < 0 || nw >= W) continue;
            if (field[nh][nw] == 0) continue;

            // 再帰的に探索
            dfs(nh, nw);
        }
    }
}

int main() {
    // 入力受け取り
    while (cin >> W >> H) {
        if (H == 0 || W == 0) break;
        field.assign(H, vector<int>(W, 0));
        for (int h = 0; h < H; ++h) for (int w = 0; w < W; ++w) cin >> field[h][w];

        // 探索開始
        int count = 0;
        for (int h = 0; h < H; ++h) {
            for (int w = 0; w < W; ++w) {
                if (field[h][w] == 0) continue; // 残島じゃなかったらスルー
                dfs(h, w);
                ++count;
            }
        }
        cout << count << endl;
    }
}

C++: #include <iostream>
#include <queue>
#include <utility>

using namespace std;

using Point = pair<int,int>;

int map[52][52];

void BFS(const Point &p0){
  queue<Point> q;
  q.push(p0);
  while(!q.empty()){
    auto p = q.front();q.pop();
    int y = p.first , x = p.second;
    map[y][x] = 0;

    for(int i=-1;i<=1;++i){
      for(int j=-1;j<=1;++j){
        if(map[i+y][j+x]){
          q.push(Point(i+y,j+x));
        }
      }
    }
  }

}

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

    int num = 0;
    for(int i=1;i<h+1;++i){
      for(int j=1;j<w+1;++j){
        if(map[i][j]){
          BFS(Point(i,j));
          num++;
        }
      }
    }
    cout << num << endl;
  }

  return 0;
}