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<vector>
#include<queue>
#include<utility>
using namespace std;

typedef pair<int, int> P;

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

int main() {
	int w, h;
	while (cin >> w >> h, w) {
		vector<vector<int>>ma(w, vector<int>(h));
		for (int i = 0; i < h;i++) {
			for (int j = 0; j < w;j++) {
				cin >> ma[j][i];
			}
		}
		int ans = 0;
		for (int i = 0; i < w;i++) {
			for (int j = 0; j < h;j++) {
				if (ma[i][j] == 1) {
					ans++;
					queue<P> q;
					q.push(P(i, j));
					ma[i][j] = 0;
					while (!q.empty()) {
						P p = q.front(); q.pop();
						for (int k = 0; k < 8; k++) {
							int nx = p.first + dx[k], ny = p.second + dy[k];
							if (nx < w && nx>=0 && ny < h && ny>=0 && ma[nx][ny]==1) {
								ma[nx][ny] = 0; q.push(P(nx, ny));
							}
						}
					}
				}
			}
		}
		cout << ans << endl;
	}
}

C++: #include <iostream>
#include <iomanip>
#include <algorithm>
#include <string>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <cstring>
#include <vector>
#include <list>
#include <map>
#include <set>
#include <queue>
#include <stack>

using namespace std;

typedef vector<int> VI;
typedef vector<vector<int> > VVI;
typedef vector<string> VS;
typedef pair<int, int> PII;
typedef pair<int, PII> PIII;

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

void dfs(VVI &table, int i, int j) {
    table[i][j] = 0;
    for (int loop = 0; loop < 8; loop++) {
        int new_i = i + dy[loop];
        int new_j = j + dx[loop];
        if (table[new_i][new_j] == 1) {
            dfs(table, new_i, new_j);
        }
    }
    return;
}

int main(void) {
    while(true) {
        int w;
        int h;
        cin >> w >> h;
        if (w == 0 && h == 0) {
            break;
        }
        VVI table(h + 2, VI(w + 2, 0));
        for (int i = 1; i <= h; i++) {
            for (int j = 1; j <= w; j++) {
                cin >> table[i][j];
            }
        }
        int number = 0;
        for (int i = 1; i <= h; i++) {
            for (int j = 1; j <= w; j++) {
                if (table[i][j] == 1) {
                    dfs(table, i, j);
                    number++;
                }
            }
        }
        cout << number << endl;
    }
    return 0;
}

C++: #include <iostream>
#include <stack>
using namespace std;
int dx[] = { -1, 0, 1, 1, 1, 0, -1, -1 };
int dy[] = { -1, -1, -1, 0, 1, 1, 1, 0 };

int main(){
	int w, h;
	while( cin >> w >> h && w && h ){
		int field[52][52];
		stack< pair<int, int> > st;
		for( int i = 1; i <= h; i++ ){
			for( int j = 1; j <= w; j++ ){
				cin >> field[i][j];
			}
		}
		int sum = 0;
		for( int i = 1; i <= h; i++ ){
			for( int j = 1; j <= w; j++ ){
				if( field[i][j] == 1 ){
					sum++;
					field[i][j] = 0;
					st.push( pair<int, int>(i, j) );
					while( !st.empty() ){
						int x0 = st.top().second;
						int y0 = st.top().first;
						st.pop();
						for( int k = 0; k < 8; k++ ){
							int x = x0 + dx[k];
							int y = y0 + dy[k];
							if( field[y][x] == 1 ){
								st.push( pair<int, int>(y, x) );
								field[y][x] = 0;
							}
						}
					}
				}
			}
		}
		cout << sum << endl;
	}
}

C++: #include <bits/stdc++.h>
using namespace std;

#define pb         push_back

const int INF = 1000000000;
const int MOD = 1000000007;

int ans;
int ma[100][100];
int w, h;

void rec(int y, int x);

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

		for(int i=0; i<h; i++){
			for(int j=0; j<w; j++){
				int t;
				cin >> t;
				ma[i][j] = t;
			}
		}

		for(int i=0; i<h; i++){
			for(int j=0; j<w; j++){
				if(ma[i][j] == 1){
					ans++;
					rec(i, j);
				}
			}
		}
		printf("%d\n", ans);

	}
	
	return 0;
}

void rec(int y, int x){
	for(int i=-1; i<=1; i++){
		for(int j=-1; j<=1; j++){
			if(i == 0 && j == 0) continue;

			int ny = y+i;
			int nx = x+j;
			if(ny >= 0 && ny < h && nx >= 0 && nx < w && ma[ny][nx] == 1){
				ma[ny][nx] = 0;
				rec(ny, nx);
			}
		}
	}
}

C++: #ifdef BUILT_LOCAL

#include "niklib.h"

#endif

#include <iostream>
#include <utility>
#include <vector>
#include <stack>
#include <queue>
#include <algorithm>
#include <string>
#include <cstdio>
#include <map>
#include <set>

using namespace std;

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

void rec(int y, int x) {
    if (y < 0 || x < 0 || y >= h || x >= w) return;
    if (c[y][x] == 0)
        return;
    c[y][x] = 0;
    for (int i = -1; i <= 1; i++) {
        for (int j = -1; j <= 1; j++) {
            rec(y + i, x + j);
        }
    }
}

int main() {
    while (1) {
        scanf("%d %d", &w, &h);
        if (w == 0 && h == 0) break;
        for (int i = 0; i < h; i++)
            for (int j = 0; j < w; j++) {
                scanf("%d", &c[i][j]);
            }
        int r = 0;
        for (int i = 0; i < h; i++)
            for (int j = 0; j < w; j++) {
                if (c[i][j] == 0) continue;
                r++;
                rec(i, j);
            }
        printf("%d\n", r);
    }
}