why is core getting dumped

Question

#include <iostream>

using namespace std;

void sk(int a[],int b[],int k,int n)
{
int count=0;
b[k-1]=1;
int m;
for(int i=0 ; i<n ;i++)
{
if(a[k-1]&a[i])
{
count++;
b[i]=1;
sk(a,b,i+1,n);
}

}

}

int main()
{
int n,k;
cin>>n>>k;
int a[n],b[n];
for(int i=0 ; i<n ;i++)
{
cin>>a[i];
b[i]=0;
}
sk(a,b,k,n);
int d;
for(int i=0 ; i<n ; i++)
if(b[i]==0)
d++;

cout<<d;

}

Answer 1

You are getting stack overflow because of infinite recursion.

if condition a[k-1]&a[i] is true for the first call then it will be true for every subsequent call:
a[k-1] is a[i_prev], where i_prev is i from previous call (caller).
i_prev can be any number in range [0...n-1].
i is iterate from 0 to n-1. So, on some iteration i will be equal to i_prev.
a[i] & a[i] is true for any nonzero a[i]. (if the first call was executed then a[k-1] has nonzero value).