Number of islands

All connected 1's (directly or diagonally) considered as one island.
see the test cases for more description.

#include<iostream>
#include<stdio.h>

int a[1000][1000];

void fun(int i,int j,int n){

if(i<0 || j<0 ||i>n-1 || j>n-1)

return;

if(a[i][j]==0)return;

a[i][j]=0;

fun(i-1,j-1,n);

fun(i-1,j,n);

fun(i,j-1,n);

fun(i-1,j+1,n);

fun(i+1,j-1,n);

fun(i+1,j,n);

fun(i,j+1,n);

fun(i+1,j+1,n);

}

using namespace std;

int main(){

int t;

scanf("%d",&t);

while(t--){

int n;

scanf("%d",&n);

for(int i=0;i<n;i++)

for(int j=0;j<n;j++)

scanf("%d",&a[i][j]);

int cnt=0;

for(int i=0;i<n;i++){

for(int j=0;j<n;j++){

    if(a[i][j]==1 )  {

    cnt++;

    fun(i,j,n);

    }

    }

    }

printf("%d\n",cnt);

}

}

Sample Input: 

2

4 
1 0 0 1 
0 0 0 0 
0 1 1 0 
1 0 0 1 

8 
0 0 1 0 0 1 0 0 
1 0 0 0 0 0 0 1 
0 0 1 0 0 1 0 1 
0 1 0 0 0 1 0 0 
1 0 0 0 0 0 0 0 
0 0 1 1 0 1 1 0 
1 0 1 1 0 1 1 0 
0 0 0 0 0 0 0 0 

Sample Output: 
3 
9