Go: ///
// File:  1160.go
// Author: ymiyamoto
//
// Created on Sun Mar  4 20:45:57 2018
//
package main

import (
	"fmt"
)

var w, h int
var graph [][]string

func dfs(visited [][]bool, x, y int) {
	visited[x][y] = true

	for i := -1; i <= 1; i++ {
		for j := -1; j <= 1; j++ {
			dx := x + i
			dy := y + j
			if 0 <= dx && dx < h && 0 <= dy && dy < w && graph[dx][dy] == "1" && !visited[dx][dy] {
				dfs(visited, dx, dy)
			}
		}
	}
}

func main() {
	for {
		fmt.Scan(&w, &h)
		if w == 0 && h == 0 {
			break
		}

		graph = make([][]string, h)
		for i := range graph {
			graph[i] = make([]string, w)
		}

		for i := 0; i < h; i++ {
			for j := 0; j < w; j++ {
				var s string
				fmt.Scan(&s)
				graph[i][j] = s
			}
		}

		visited := make([][]bool, h)
		for i := range visited {
			visited[i] = make([]bool, w)
		}

		count := 0
		for i := range graph {
			for j := range graph[i] {
				if graph[i][j] == "1" && !visited[i][j] {
					dfs(visited, i, j)
					count++
				}
			}
		}

		fmt.Println(count)
	}
}

C++: /*
URL: http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=1160&lang=jp
?????????: How Many Islands?
?????°:
18:49 ?????????????????????????§£?????????
*/
#include <iostream>
using namespace std;

int dat[52][52]; // ??¨?????????1???????????£?????°

void delete_island_from(int i, int j)
{
	int dx[8] = {-1,-1,-1, 0,  0, 1, 1, 1};
	int dy[8] = {-1, 0, 1,-1,  1,-1, 0, 1};

	dat[i][j] = 0;
	for(int k=0;k<8;k++) {
		if(dat[i+dx[k]][j+dy[k]]) {
			delete_island_from(i+dx[k],j+dy[k]);
		}
	}
}


int main()
{
	while(true){ // data set
		//dat???0????????¢
		for(int i=0;i<52;i++){
			for(int j=0;j<52;j++){
				dat[i][j]=0;
			}
		}

		int w; int h;
		cin >> w >> h;
		if(w == 0 && h == 0) {break;}

		for(int i=0; i<h;i++) {
			for(int j=0;j<w;j++) {
				cin >> dat[i+1][j+1]; // ??¨?????????1???????????£?????°
			}
		}

		int ans = 0;
		while(true) {
			for(int i=0; i<h+2;i++) { // ????????£?????°??????
				for(int j=0;j<w+2;j++) {
					if(dat[i][j] == 1){
						delete_island_from(i,j);
						ans++;
						goto label1;
					}
				}
			} // all is ocean
			cout << ans << endl;
			break;


			label1: ;
		}
	}
}

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

int main() {
    while (true) {
        bool seen[100][100] = {false};
        vector<vector<int>> field;
        stack<pair<int, int>> to_visit;
        int cnt = 0;

        int w, h;
        cin >> w >> h;

        if (w == 0 || h == 0) {
            break;
        }

        field.assign(h, vector<int>(w, 0));
        for (int i = 0; i < h; i++) {
            for (int j = 0; j < w; j++) {
                cin >> field[i][j];
            }
        }

        // for (int i = 0; i < h; i++) {
        //     for (int j = 0; j < w; j++) {
        //         if (field[i][j] == 0) {
        //             cout << "^";
        //         }
        //         else {
        //             cout << "O";
        //         }
        //     }
        //     cout << endl;
        // }

        for (int i = 0; i < h; i++) {
            for (int j = 0; j < w; j++) {
                if (field[i][j] == 0) {
                    continue;
                }
                if (seen[i][j] == true) {
                    continue;
                }

                cnt++;
                to_visit.push(make_pair(i, j));
                seen[i][j] = true;
                while (to_visit.empty() == false) {
                    pair<int, int> cur_pos = to_visit.top(); to_visit.pop();
                    int cur_h = cur_pos.first;
                    int cur_w = cur_pos.second;
                    for (int dh = -1; dh <= 1; dh++) {
                        for (int dw = -1; dw <= 1; dw++) {
                            if (dh == 0 && dw == 0) {
                                continue;
                            }

                            int next_h = cur_h + dh;
                            int next_w = cur_w + dw;
                            if (next_h < 0 || next_h >= h || next_w < 0 || next_w >= w) {
                                continue;
                            }
                            if (seen[next_h][next_w] == true) {
                                continue;
                            }
                            if (field[next_h][next_w] == 0) {
                                continue;
                            }
                            to_visit.push(make_pair(next_h, next_w));
                            seen[next_h][next_w] = true;
                        }
                    }
                }
            }
        }

        cout << cnt << endl;
    }

    return 0;
}

C++: #include <iostream>
#include <cstdio>
#include <cstdlib>

using namespace std;

#define MAX_L 50

int graph[MAX_L+2][MAX_L+2];

void search(int x, int y, int num){
	graph[x][y]=num;
	for(int i=-1; i<=1; i++){
	    for(int j=-1; j<=1; j++){
	      if(graph[x+i][y+j] == 1){search(x+i, y+j, num);}
	    }
	}
}

int main()
{
	int w, h, label;
 
	while(true){
		scanf("%d%d\n",&w, &h);
		if(w==0 && h==0){return 0;}

		for(int i=0; i<h+2; i++){
			for(int j=0; j<w+2; j++){
				graph[i][j]=0;
			}
		}

		for(int i=1; i<h+1; i++){
			for(int j=1; j<w+1; j++){
				cin >> graph[i][j];
			}
		}

		label = 1;
		for(int i=1; i<h+1; i++){
			for(int j=1; j<w+1; j++){
				if(graph[i][j]==1){
					label++;
					search(i,j,label);
				}
			}
		}
		cout << label-1 << endl;		
	}	
}