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>
#define rep(i, n) for(int i = 0; i < (n); ++i)
using namespace std;
using ll = long long;
using IslandsMap = vector<vector<int>>;
using CheckMap = vector<vector<bool>>;

int direction_x[8] = {0, 1, 1, 1, 0, -1, -1, -1};
int direction_y[8] = {1, 1, 0, -1, -1, -1, 0, 1};

int h,w;
IslandsMap islands_map;
CheckMap check_map;

void dfs(int x, int y) {
    int dx, dy;
    check_map[y][x] = true;
    rep(i, 8) {
        dx = x + direction_x[i];
        dy = y + direction_y[i];
        if(dx >= 0 && dx < w && dy >= 0 && dy < h &&
           check_map[dy][dx] == false && islands_map[dy][dx] == 1) {
            dfs(dx, dy);
        }
    }
}

int countIslands() {
    int ans = 0;
    rep(y, h) {
        rep(x, w) {
            if(check_map[y][x] == false && islands_map[y][x] == 1) {
                dfs(x, y);
                ans++;
            }
        }
    }
    return ans;
}

int main() {
    // 制約見て！！！デカかったらlong longにすること！
    int c;
    while(true) {
        cin >> w >> h;
        if(w == 0 && h == 0)
            break;

        islands_map.resize(h);
        rep(i, h) {
            islands_map[i].resize(w);
            rep(j, w) {
                cin >> c;
                islands_map[i][j] = c;
            }
        }

        check_map.resize(h);
        rep(i, h) {
            check_map[i].resize(w);
            check_map[i].assign(w,false);
        }
        cout << countIslands() << endl;
    }
}

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

using namespace std;

int main(void) {
	int w,h;
	while(cin >> w >> h && w && h) {
		vector< vector<int> > data(w+2,vector<int>(h+2));
		vector< vector<bool> > check(w+2,vector<bool>(h+2,false));
		queue<int> sx,sy;
		for (int i = 0; i < h + 2; ++i) {
			for (int j = 0; j < w + 2; ++j) {
				if (i == 0 || i == h+1 || j == 0 || j == w+1) {
					data[i][j] = 0;
				}
				else {
					cin >> data[i][j];
					if (data[i][j] == 1) {
						sx.push(j);
						sy.push(i);
					}
				}
			}
		}

		int nx,ny;
		int count = 0;
		queue<int> fx,fy;
		while(!sx.empty()) {
			nx = sx.front();
			ny = sy.front();
			sx.pop();
			sy.pop();
			if (!check[ny][nx]) {
				check[ny][nx] = true;
				fx.push(nx);
				fy.push(ny);
				++count;
			}
			while (!fx.empty()) {
				nx = fx.front();
				ny = fy.front();
				fx.pop();
				fy.pop();
				if (!check[ny+1][nx] && data[ny+1][nx] == 1) {
					check[ny+1][nx] = true;
					fx.push(nx);
					fy.push(ny+1);
				}
				if (!check[ny-1][nx] && data[ny-1][nx] == 1) {
					check[ny-1][nx] = true;
					fx.push(nx);
					fy.push(ny-1);
				}
				if (!check[ny+1][nx+1] && data[ny+1][nx+1] == 1) {
					check[ny+1][nx+1] = true;
					fx.push(nx+1);
					fy.push(ny+1);
				}
				if (!check[ny+1][nx-1] && data[ny+1][nx-1] == 1) {
					check[ny+1][nx-1] = true;
					fx.push(nx-1);
					fy.push(ny+1);
				}
				if (!check[ny-1][nx-1] && data[ny-1][nx-1] == 1) {
					check[ny-1][nx-1] = true;
					fx.push(nx-1);
					fy.push(ny-1);
				}
				if (!check[ny-1][nx+1] && data[ny-1][nx+1] == 1) {
					check[ny-1][nx+1] = true;
					fx.push(nx+1);
					fy.push(ny-1);
				}
				if (!check[ny][nx+1] && data[ny][nx+1] == 1) {
					check[ny][nx+1] = true;
					fx.push(nx+1);
					fy.push(ny);
				}
				if (!check[ny][nx-1] && data[ny][nx-1] == 1) {
					check[ny][nx-1] = true;
					fx.push(nx-1);
					fy.push(ny);
				}
			}
		}
		cout << count << endl;
	}
	return 0;
}