Turn the floor plan a quarter turn
A layout tool rotates a square plan ninety degrees clockwise so it fits the room the other way round.
- The plan is square.
- The top row becomes the right-hand column, read downwards.
- An empty plan comes back empty.
rotateClockwise(plan: list<list<int>>) → list<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 rotateClockwise(plan [][]int) [][]int {
}Worked examples
| Call | Result |
|---|---|
rotateClockwise([][]int{[]int{1, 2}, []int{3, 4}}) | [][]int{[]int{3, 1}, []int{4, 2}} |
rotateClockwise([][]int{[]int{1, 2, 3}, []int{4, 5, 6}, []int{7, 8, 9}}) | [][]int{[]int{7, 4, 1}, []int{8, 5, 2}, []int{9, 6, 3}} |
rotateClockwise([][]int{[]int{1}}) | [][]int{[]int{1}} |
rotateClockwise([][]int{}) | [][]int{} |
Hint
The cell at row r, column c lands at row c, column (last - r). Building a fresh grid is easier to get right than shuffling in place.
Reference solution in Go
func rotateClockwise(plan [][]int) [][]int {
n := len(plan)
turned := [][]int{}
for r := 0; r < n; r++ {
row := []int{}
for c := 0; c < n; c++ {
row = append(row, plan[n-1-c][r])
}
turned = append(turned, row)
}
return turned
}