Reverse a list end to end
A replay view shows the most recent reading first, so the buffer has to come back the other way round.
- The order reverses; the values themselves are untouched.
- An empty list and a single reading both come back as they went in.
reverseReadings(readings: list<int>) → list<int>
Go needs a compiler and Drill does not host one yet, so this page is the reference rather than an exercise: the problem, worked examples, and the solution in full. To type it out, the same problem runs in Python.
Where you start
func reverseReadings(readings []int) []int {
}Worked examples
| Call | Result |
|---|---|
reverseReadings([]int{1, 2, 3}) | []int{3, 2, 1} |
reverseReadings([]int{1, 2, 3, 4}) | []int{4, 3, 2, 1} |
reverseReadings([]int{7}) | []int{7} |
reverseReadings([]int{}) | []int{} |
Hint
Put one index at each end. Swap what they point at, then step them towards each other until they meet.
Reference solution in Go
func reverseReadings(readings []int) []int {
out := append([]int{}, readings...)
i, j := 0, len(out)-1
for i < j {
out[i], out[j] = out[j], out[i]
i++
j--
}
return out
}