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>
using namespace std;
typedef pair<int, int> P;

int main(void){
  int w, h;
  int num=0;
  int map[51][51];
  int dir[8][2]={{1,0},{1,1},{1,-1},{0,1},{0,-1}, {-1,0},{-1,1},{-1,-1}};
  queue<P> que;
  cin >> w >> h;
  while(w+h){
    //input
    for (size_t y = 0; y < h; y++) {
      for (size_t x = 0; x < w; x++) {
        cin >> map[y][x];
      }
    }

    //output
    for (size_t y = 0; y < h; y++) {
      for (size_t x = 0; x < w; x++) {
        if (map[y][x]==1) {
          //search islands & added que & replace 0
          que.push(P(y, x));
          map[y][x]=0;
          while(que.size()){
            P p = que.front(); que.pop();
            for (size_t i = 0; i < 8; i++) {
              if (0<=p.first+dir[i][0] && p.first+dir[i][0]<h &&
              0<=p.second+dir[i][1] && p.second+dir[i][1]<w) {
                if(map[ p.first+dir[i][0] ][ p.second+dir[i][1] ]==1){
                  //added que & replace 0
                  que.push(P(p.first+dir[i][0], p.second+dir[i][1]));
                  map[ p.first+dir[i][0] ][ p.second+dir[i][1] ]=0;
                }
              }
            }
          }
          num+=1;
        }
      }
    }
    cout << num << endl;
    cin >> w >> h;
    num=0;
  }
  return 0;
}