Give each sequence its own pointer
Updated
Two sequences get two independent indices: i on a, j on b. They are not L and R on one array. Each pointer only reads its own sequence.
What to focus on
i is legal only for a (0..a.length-1). j is legal only for b. Moving i never changes j. A shorter partner still starts at 0.
Worked examples
both nonempty
a = [1, 4, 9], b = [4, 7]- i ← 0 on a
- j ← 0 on b
- heads 1 and 4
Result: i=0, j=0
b shorter
a = [1, 4, 9], b = [4]- i ← 0
- j ← 0
- b has no index 1
Result: i=0, j=0 · b last is 0
empty b
a = [1, 4, 9], b = []- i ← 0 is legal
- j has nowhere to sit
Result: i=0, no j
Try it
Write placeTwoSeq(a, b). a is an array of integers. b is a second array of integers. i is the index on a. j is the index on b. Set i = 0 and j = 0. Print i and j. Each pointer stays on its own array. On a = [1, 4, 9] with b = [4, 7], with b = [4], and a = [1] with b = [4, 7, 9], print i=0, j=0.
a and b are nonempty arrays.