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<cstring>
#include<queue>

typedef std::pair<int, int> P;
int vx[] = { 0, 1, 0, -1, 1, 1, -1, -1 }, vy[] = { 1, 0, -1, 0, 1, -1, 1, -1 };
int w, h;
int map[51][51];

void bfs(int x, int y){

	map[y][x] = 0;

	std::queue<P>que;
	que.push(P(x, y));

	while (!que.empty()){

		P p = que.front();
		que.pop();

		for (int i = 0; i < 8; i++){
			int nx = p.first + vx[i], ny = p.second + vy[i];

			if (0 <= nx&&nx < w && 0 <= ny&&ny < h&&map[ny][nx] != 0){
				map[ny][nx] = 0;
				que.push(P(nx, ny));
			}
		}
	}

	return;
}

int main(){

	while (std::cin >> w >> h, w || h){

		int cnt = 0;

		memset(map, 0, sizeof(map));
	
		for (int i = 0; i < h; i++){
			for (int j = 0; j < w; j++){
				std::cin >> map[i][j];
			}
		}

		for (int i = 0; i < h; i++){
			for (int j = 0; j < w; j++){
				if (map[i][j] != 0){
					bfs(j, i);
					cnt++;
				}
			}
		}

		std::cout << cnt << std::endl;
	}

	return 0;
}

C++: #include <iostream>
using namespace std;
int w, h;
int c[55][55];

void dfs(int y, int x) {
    c[y][x] = 0;
    for (int dh = -1; dh <= 1; dh++) {
        for (int dw = -1; dw <= 1; dw++) {
            int nh = y + dh, nw = x + dw;
            if (0 <= nh && 0 <= nw && nh < h && nw < w && c[nh][nw]) {
                dfs(nh, nw);
            }
        }
    }
}

int main() {
    while (cin >> w >> h) {
        if (w == 0 && h == 0) break;
        for (int i = 0; i < h; i++) {
            for (int j = 0; j < w; j++) cin >> c[i][j];
        }
        int ans = 0;
        for (int i = 0; i < h; i++) {
            for (int j = 0; j < w; j++) {
                if (c[i][j]) {
                    ans++;
                    dfs(i, j);
                }
            }
        }
        cout << ans << endl;
    }
}

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

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

int fill(vector<vector<bool> >& map, int y, int x){
    if(!map[y][x]) return 0;
    map[y][x] = false;
    for(int i=0; i<8; i++){
        fill(map, y+dy[i], x+dx[i]);
    }
    return 1;
}
        
int main(){
    while(1){
        int w,h;
        cin >> w >> h;
        if(w==0) break;

        vector<vector<bool> > map(h+2, vector<bool>(w+2, false));
        for(int i=1; i<=h; i++){
            for(int j=1; j<=w; j++){
                int tmp;
                cin >> tmp;
                if(tmp==1) map[i][j]=true;
            }
        }

        int count=0;
        for(int i=1; i<=h; i++){
            for(int j=1; j<=w; j++){
                count+= fill(map, i,j);
            }
        }
        cout << count << endl;
    }   
    return 0;
}

C++: //
//AOJ vol11-1160
//http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=1160&lang=jp
//20170616
//640009E
//Yang Bo
//

#include <iostream>

using namespace std;

int a[50][50];
int h, w;

int recursion(int y, int x)
{
  int number = 1;
  a[y][x] = 0;

  if (x < w - 1)
    if (a[y][x + 1] == 1)
      number = recursion(y, x + 1);
  if (y < h - 1)
    if (a[y + 1][x] == 1)
      number = recursion(y + 1, x);
  if (x > 0)
    if (a[y][x - 1] == 1)
      number = recursion(y, x - 1);
  if (y > 0)
    if (a[y - 1][x] == 1)
      number = recursion(y - 1, x);
  if (y < h - 1 && x < w - 1)
    if (a[y + 1][x + 1] == 1)
      number = recursion(y + 1, x + 1);
  if (y < h - 1 && x > 0)
    if (a[y + 1][x - 1] == 1)
      number = recursion(y + 1, x - 1);
  if (y > 0 && x < w - 1)
    if (a[y - 1][x + 1] == 1)
      number = recursion(y - 1, x + 1);
  if (y > 0 && x > 0)
    if (a[y - 1][x - 1] == 1)
      number = recursion(y - 1, x - 1);
  

  //cout << "recursion(" << y << ", "<< x << ") = " << number << endl;
  return number;
}

int main()
{
  while (cin >> w >> h) {
    if (w == 0)
      break;
    else {
      for (int i = 0; i < h; i++) {
	for (int j = 0; j < w; j++) {
	  cin >> a[i][j]; //??\???
	}
      }
      int ans = 0;
      for (int i = 0; i < h; i++) {
	for (int j = 0; j < w; j++) {
	  if (a[i][j] == 1) {
	    //cout << "i = " << i << " ,j = " << j << endl;
            ans += recursion(i, j);
	  }
	}
      }
      cout << ans << endl;
    }
  }
}

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