Please explain this code line by line and how the values of each variable changes as you go down the code.

#include
#include
using namespace std;

int main() {
int a[] = {0, 0, 0};

int* p = &a[1];
int* q = &a[0];

q=p;
q=1;

p = a;
p=1;

int*& r = p;
int** s = &q;

r = *s + 1;
s= &r;

**s = 1;

return 0;
}

int* p = &a[1]; //pointer p is initialized it will be holding the address of a1 which means when p will be called it will point to whatever is present at the address a1, right now it hold 0.

int* q = &a[0]; //pointer q is initialized it will be holding the address of a0 which means when q will be called it will point to whatever is present at the address a0, right now it hold 0.

q=p; // now q is also pointing towards what p is pointing both holds the same address that is &a[1]

*q=1 ; //&a[0] gets overwritten and now pointer q has integer 1......i am not sure abut this one

p = a; //p is now holding address of complete array a

*p=1; // a gets overwritten and now pointer q has integer 1......i am not sure abut this one

int*& r = p; //not sure

int** s = &q; s is a double pointer means it has more capacity of storage than single pointer and is now holding address of q

r = *s + 1; //not sure

s= &r; //explained above

**s = 1; //explained above

return 0;

}