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

using ll = long long;
using ull = unsigned long long;
using st = string;
using db = double;
using vll = vector<long long>;
using vb = vector<bool>;
using vvll = vector<vll>;
using vst = vector<st>;
using vchar = vector<char>;
#define rep(i, m, n) for (int i = (int)(m); i < (int)(n); i++)
#define vrep(i, vec) for(auto& i : vec)
#define vin(vec) for(auto& i : vec) cin >> i
#define all(v) v.begin(), v.end()
ll mod = 1000000007;

ll w, h;
vvll graph;

void dfs(vvll &graph, ll x, ll y){
  graph[y][x] = 2;
  rep(dx, -1, 2) rep(dy, -1, 2)if(x + dx >= 0 && x + dx < w && y + dy >= 0 && y + dy < h)if(graph[y + dy][x + dx] == 1) dfs(graph, x + dx, y + dy);
}

int main(){
  while(true){
  cin >> w >> h;
  if(w == 0 && h == 0) break;
  graph.assign(h, vll(w));
  rep(y, 0, h)rep(x, 0, w) cin >> graph[y][x];
  ll ans = 0;
  rep(y, 0, h)rep(x, 0, w){
    if(graph[y][x] == 1){
      dfs(graph, x, y);
      ans++;
    }
  }
  cout << ans << endl;}
}

C++: #include <stdio.h>

int W,H,ans;
int map[100][100];

void search_island(int x, int y){
	map[x][y] = 0;
	if(x > 0){
		if(map[x - 1][y]){
			search_island(x - 1, y);
		}
	}
	if(x < H - 1){
		if(map[x + 1][y]){
			search_island(x + 1, y);
		}
	}
	if(y > 0){
		if(map[x][y - 1]){
			search_island(x, y - 1);
		}
	}
	if(y < W - 1){
		if(map[x][y + 1]){
			search_island(x, y + 1);
		}
	}
}


int main()
{
	scanf("%d %d",&W,&H);
	while(W != 0 && H != 0){
		for(int i = 0; i < H; i++){
			for(int k = 0; k < W; k++){
				scanf("%d",&map[i][k]);
			}
		}

		ans = 0;

		for(int j = 0; j < H; j++){
			for(int k = 0; k < W; k++){
				if(map[j][k]){
					ans++;
					search_island(j,k);
				}
			}
		}

		printf("%d\n",ans);
		scanf("%d %d",&W,&H);
	}
	return 0;
}

C++: #include <bits/stdc++.h>
#include <cstdint>
#include <sys/time.h>

typedef std::int_fast32_t  s32;
typedef std::uint_fast32_t u32;
typedef std::int_fast64_t  s64;
typedef std::uint_fast64_t u64;

typedef std::pair<int, int> P;

int map[64][64];
int H, W;

void dfs_erase(int x, int y) {
  if( not ( 0 <= x and x < H and 0 <= y and y < W ) ) return;
  if( not ( map[x][y] == 1 ) ) return;

  map[x][y] = 0;
  
  int dx[8] = {1, 1, 1, 0, 0, -1, -1, -1};
  int dy[8] = {1, 0, -1, 1, -1, 1, 0, -1};
  for(int i = 0; i < 8; ++i) {
    dfs_erase(x + dx[i], y + dy[i]);
  }
  return;
}
  
int main(void) {

  for(;;) {
    std::cin >> W >> H;
    if( W == 0 and H == 0 ) break;

    for(int i = 0; i < H; ++i) {
      for(int j = 0; j < W; ++j) {
        std::cin >> map[i][j];
      }
    }

    int res = 0;
    for(int i = 0; i < H; ++i) {
      for(int j = 0; j < W; ++j) {
        if( map[i][j] == 1 ) {
          dfs_erase(i, j);
          res += 1;
        }
      }
    }

    std::cout << res << std::endl;
  }
  
  return 0;
}

C++: #include<stdio.h>
void printmap();
void draw(int x,int y);
int w,h,c[50][50];

int main(){
	int i,j;
	int count;


	scanf("%d %d",&w,&h);


	while((w!=0)&&(h!=0)){
		count=0;
	
		for(j=0;j<h;j++){
			for(i=0;i<w;i++){
				scanf("%d",&c[j][i]);
			}
		}
		//printf("\n");
		//printmap();
	
		for(i=0;i<w;i++){
			c[h][i]=0;
		}
		for(i=0;i<h;i++){
			c[i][w]=0;
		}

		for(i=0;i<w;i++){
			for(j=0;j<h;j++){
				if(c[j][i]==1){
					count++;
					//printf("count up count=%d\n",count);
					draw(j,i);
				}
			}
		}

		printf("%d\n",count);
		scanf("%d %d",&w,&h);
	}
	return 0;
}

void draw(int x,int y){
	//printf("delete %d %d\n",x,y);
	c[x][y]=0;
	if(c[x+1][y]==1){
		draw(x+1,y);
	}else if(c[x-1][y]==1){
		draw(x-1,y);
	}else if(c[x][y-1]==1){
		draw(x,y-1);
	}else if(c[x][y+1]==1){
		draw(x,y+1);
	}

}

void printmap(){
	int i,j;
	for(j=0;j<h;j++){
		for(i=0;i<w;i++){
			printf("%d ",c[j][i]);
		}
		printf("\n");
	}
}

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

bool isprime(int n){
    double rootn = sqrt(n);
    if (n < 2){
        return false;
    }
    else if (n == 2){
        return true;
    }
    else if (n % 2 == 0){
        return false;
    }
    else{
        for(int i = 3; i <= rootn; i += 2){
            if(n % i == 0){
                return false;
            }
        }
        return true;
    }
}

// 空のベクトルを二つ渡す。N (>=2) 以下の素数を primes に順番に入れる。
void prime_vectors(int N, vector<int>& primes, vector<bool>& is_prime){
    primes = {};
    is_prime = {};
    for(int i=0; i<=N; i++){
        is_prime.push_back(true);
    }

    primes.push_back(2);
    for(int j=4; j<=N; j+=2){
        is_prime[j] = false;
    }

    int i;
    for(i=3; i*i<=N; i+=2){
        if(!is_prime[i]) continue;
        primes.push_back(i);
        for(int j=2*i; j<=N; j+=i){
            is_prime[j] = false;
        }
    }

    for(; i<=N; i+=2){
        if(is_prime[i]){
            primes.push_back(i);
        }
    }
}

signed main(){
    // cout << fixed << setprecision(10) << flush;

    int w, h;
    cin >> w >> h;
    vector<int> n_cc;
    while(w != 0 && h != 0){
        vector<vector<int>> c(h+2, vector<int>(w+2, 0));
        for(int i=1; i<=h; i++){
            for(int j=1; j<=w; j++){
                cin >> c[i][j];
            }
        }

        int visited[h+2][w+2] = {0};
        stack<pair<int, int>> stk;
        int cc = 0;
        for(int i=1; i<=h; i++){
            for(int j=1; j<=w; j++){
                if(c[i][j] == 0 || visited[i][j] == 1) continue;
                visited[i][j] = 1;
                stk.push(make_pair(i, j));
                while(!stk.empty()){
                    int i0 = stk.top().first, j0 = stk.top().second;
                    stk.pop();
                    for(int id=-1; id<=1; id++){
                        for(int jd=-1; jd<=1; jd++){
                            if(c[i0+id][j0+jd] == 1 && visited[i0+id][j0+jd] == 0){
                                visited[i0+id][j0+jd] = 1;
                                stk.push(make_pair(i0+id, j0+jd));
                            }
                        }
                    }
                }

                cc++;
            }
        }
        n_cc.push_back(cc);

        cin >> w >> h;
    }

    for(int i=0; i<n_cc.size(); i++){
        cout << n_cc[i] << endl;
    }

    return 0;
}