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<cstdio>
using namespace std;
int mas[100][100];
int dx[8]={1,1,0,-1,-1,-1,0,1},dy[8]={0,1,1,1,0,-1,-1,-1};
int sx,sy,gx,gy,w,h,cnt=0;
void dfs(int x,int y);
int main(){
  while(1){
    cnt=0;
  cin >> w >> h;
  if(w==0 && h==0) break;
  for(int i=0;i<h;i++){
    for(int j=0;j<w;j++){
      cin >> mas[i][j];
    }
  }
  for(int i=0;i<h;i++){
    for(int j=0;j<w;j++){
      if(mas[i][j]==1){
        cnt++;
        dfs(j,i);
      }
    }
  }
  cout << cnt << endl;
  }
}
void dfs(int x,int y){
  mas[y][x]=0;
  for(int i=0;i<8;i++){
    int nx=x+dx[i];
    int ny=y+dy[i];
    if(nx >= 0&& nx < w && ny >= 0 && ny < h && mas[ny][nx]==1){
        dfs(nx,ny);
      }
  }
}

C++: #include<cstdio>
#include<cstdlib>
#include<ctime>
#include<cmath>
#include<cstring>
#include<cctype>
#include<complex>
#include<iostream>
#include<sstream>
#include<algorithm>
#include<functional>
#include<vector>
#include<string>
#include<stack>
#include<queue>
#include<map>
#include<set>
#include<bitset>
using namespace std;
 
const int dx[] = {1,1,0,-1,-1,-1,0,1};
const int dy[] = {0,1,1,1,0,-1,-1,-1};
#define INF 1e+8
#define EPS 1e-10
#define PB push_back
#define fi first
#define se second
#define ll long long 
#define reps(i,j,k) for(int i = (j); i < (k); i++)
#define rep(i,j) reps(i,0,j)
typedef pair<int,int> Pii;
typedef vector<int> vi;
void solve(int y,int x,int h,int w,int stage[52][52]){
    rep(i,8){
        int nx = x + dx[i];
        int ny = y + dy[i];
        if(nx < 0 || nx > w-1 || ny < 0 || ny > h-1 || stage[ny][nx] == 0)continue;
        stage[ny][nx] = 0;
        solve(ny,nx,h,w,stage);
    }
    return ;
}
int main(){
    int w,h;
    while(scanf("%d%d",&w,&h),w){
        int stage[52][52]={{0}};
        int ans = 0;
        rep(i,h){
            rep(j,w){
                scanf("%d",&stage[i][j]);
            }
        }
        rep(i,h){
            rep(j,w){
                if(stage[i][j] == 1){
                    stage[i][j] = 0;
                    solve(i,j,h,w,stage);
                    ans++;
                }
            }
        }
        printf("%d\n",ans);
    }
    return 0;
}

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

#define rep(i, n)	for(int i = 0; i < (int)(n); i++)
#define ull unsigned long long

struct Data {
	int x, y, n;
};

int w, h;
int c[51][51];
stack<Data> st;

void land_dfs(int x, int y, int n) {
	

	c[x][y] = n;

	// 島の発見中
	// 周囲8マスに島チェック

	for (int yy = -1; yy <= 1; yy++) {
		for (int xx = -1; xx <= 1; xx++) {
			if (x + xx < 0 || x + xx >(w - 1)) continue;
			if (y + yy < 0 || y + yy >(h - 1)) continue;
			if (c[x + xx][y + yy] != 1) continue;

				st.push({ x + xx, y + yy, n });

		}
	}

}

int main() {

	while (true) {
		cin >> w >> h;
		if (w == 0 &&  h == 0) break;

		int count = 0;

		for (int y = 0; y < h; y++) {
			for (int x = 0; x < w; x++) {
				cin >> c[x][y];
			}
		}

		for (int y = 0; y < h; y++) {
			for (int x = 0; x < w; x++) {
				if (c[x][y] == 1) {
					count++;
					st.push({ x, y, count + 1 });


					while (!st.empty()) {
						const auto d = st.top();
						st.pop();
						land_dfs(d.x, d.y, d.n);
					}
				}
			}
		}

		cout << count << endl;
	}


	return 0;
}

C++: #include <bits/stdc++.h>

using namespace std;

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

void dfs(int x, int y, vector<vector<bool> >& Cango){
  
  Cango[x][y] = false;
  

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

  }
}

int main(void)
{
  
  int w, h;
  int si, sj;
  while(1){
    cin >> w >> h;
    if(w == 0 && h == 0) break;

    vector<vector<bool> > Cango(h + 2, vector<bool>(w + 2, false));
    for(int i = 1 ; i <= h; i++){
      for(int j = 1; j <= w; j++){
	int input; cin >> input;
       Cango[i][j] = input;
      }
    }
    
    int counter = 0;

    for(int i = 1; i <= h; i++){
      for(int j = 1; j <= w; j++){
        if(Cango[i][j] == true){
          counter++;
           dfs(i, j, Cango);
         }
       }
     }
    cout << counter << endl;
  }

  return 0;
    
}

C++: #include<iostream>
#include<iomanip>
#include<cstdlib>
#include<stdio.h>
#include<time.h>
#include<math.h>
#include<algorithm>
#include<string>
#include<vector>
#include<list>
#include<queue>
#include<stack>
#include<deque>
#include<set>
#include<map>
#define REP(i, N) for(ll i = 0; i < N; ++i)
#define FOR(i, a, b) for(ll i = a; i < b; ++i)
#define ALL(a) (a).begin(),(a).end()
#define pb push_back
#define INF 1000000000
#define MOD 1000000007
using namespace std;
typedef long long ll;
typedef pair<ll, ll> P;
int dx[4] = {1, 0, -1, 0};
int dy[4] = {0, 1, 0, -1};
int qx[8] = {1, 1, 0, -1, -1, -1, 0, 1};
int qy[8] = {0, 1, 1, 1, 0, -1, -1, -1};

vector<vector<int> > m;
int w, h;

void cal(ll x, ll y) {
	REP(i, 8) {
		ll nx = x + qx[i];
		ll ny = y + qy[i];
		if(nx >= 0 && nx < h && ny >= 0 && ny < w && m[nx][ny] == 1) {
			m[nx][ny] = 0;
			cal(nx, ny);
		}
	}
}

int main(void) {
	while(true) {
		cin>>w>>h;
		if(w == 0 && h == 0) break;
		m.resize(h);
		REP(i, h) {
			m[i].resize(w);
		}
		REP(i, h) {
			REP(j, w) {
				cin>>m[i][j];
			}
		}
		ll ans = 0;
		REP(i, h) {
			REP(j, w) {
				if(m[i][j] == 1) {
					++ans;
					cal(i, j);
				}
			}
		}
		cout<<ans<<endl;
	}
}