https://leetcode.com/problems/rotate-array/
python
class Solution:
def rotate(self, A: List[int], k: int) -> None:
#reverse the whole
N=len(A)
k=k%N
for i in range(N//2):
A[i],A[N-1-i]=A[N-1-i],A[i]
#reverse [0:k]
for i in range(k//2):
A[i],A[k-1-i]=A[k-1-i],A[i]
#reverse [k:]
for i in range((N-k)//2):
A[k+i],A[N-1-i]=A[N-1-i],A[k+i]It can be simplified:
python
class Solution:
def rotate(self, A: List[int], k: int) -> None:
def reverse(i,j):
while i<j:
A[i],A[j]=A[j],A[i]
i,j=i+1,j-1
N=len(A)
k=k%N
#reverse the whole
reverse(0,N-1)
#reverse first k
reverse(0,k-1)
#reverse last k
reverse(k,N-1)