Answer 1

Do you possess satisfactory knowledge of Sets?

In union, the new set = set a + set b elements (Common or not).

So we add the arrays by storing in a new array. First we copy the first set a, then the set b. This way, we are able to store the union.

for(i=0; i<m; i++) 
{ R[i] = A[i]; l++; } //Copying set 1.
int e = l;
for(i=0; i<n; i++) 
{ int found=0;
/* Now, found is used to check if we are accidently copying a number again from set 2 thats already copied from set 1. Thus, its a marker */
for(int j=0; j<e; j++) 
{ if (B[i] == R[j]) //If we have a match in our data...
{ found = 1; break; } } //Don't copy that element.
if (found==0) //Otherwise...
{ R[l] = B[i]; l++; } } //Copy it and increase the size.