Answer 1

One way to think of arrays is like regular variables.
int a0, a1, a2, a3, a4, a5, a6, a7, a8, a9;
is identical to the following:
int a[10];
you can reference them individually like:
a[7] = a7;
a[5] = a5;
The main advantage to arrays is using loops to access them.
I've included all my array and pattern codes, which have reasonable comments so should help you understand them.
https://code.sololearn.com/c9c17qrFsFZ1
https://code.sololearn.com/cpXOvM9U4w80
https://code.sololearn.com/cAuablJG3TRE
https://code.sololearn.com/cNI2QYCm2KKc
https://code.sololearn.com/cwDnUNGbcc1m
https://code.sololearn.com/cZJlptyFC3VB
https://code.sololearn.com/cXwd3fTP5N95
https://code.sololearn.com/cK2TmeNjXe1q