Read the pair at both pointers
Updated
Reading the pair looks at a[L] and a[R] without moving. The pair is two values and two indices. You do not write.
What to focus on
L and R must both be in range. If L == R you are reading one cell twice, only legal if the problem allows a self-pair.
Worked examples
opposite
a = [4, 1, 9], L=0, R=2- L=0, R=2
- read a[0]=4 and a[2]=9
Result: (4, 9) at (0, 2)
adjacent
a = [4, 1, 9], L=0, R=1- L=0, R=1
- read 4 and 1
Result: (4, 1) at (0, 1)
empty
a = []- no in-range L or R
- do not invent a pair
Result: no pair
Try it
Write readPair(a, L, R). a is an array of integers. L is the left index. R is the right index. Print values and indices. Do not move the pointers. Return nothing. On [4, 1, 9] at (0, 2) print (4, 9). At (0, 1) print (4, 1). At (1, 1) print (1, 1).
a may be empty. L and R are in-range indices.