I seek explanation of following question

Question

#include<stdio.h>
void function1(int**,int**);
int main()
{
int a=5,b=7;
int *p,*q;
p=&a,q=&b;
function1(&p,&q);
printf("%d %d %d %d",*p,*q,a,b);

return 0;
}
void function1(int **p,int **q)
{
int **t;
*t=*p;
**p=**q+**p;
*p=*q;
**q=**p-**q;
*q=*t;
**p=**p-**q;
}

Answer 1

the function part is use to swap 2 numbers, if you understand pointer, explaining further won't be a problem but am just kind of lazy to type😉😉😉