gistfile1.txt

class Solution:

    def rotateString(self, A, offset):
        if A is None or len(A) == 0:
            return A

        offset %= len(A)
        self.reverse(A, 0, len(A)-offset-1)
        self.reverse(A, len(A)-offset, len(A)-1)
        self.reverse(A, 0, len(A)-1)
        return A

    def reverse(self, str, start, end):
        
        while start < end :            
            str[start], str[end] = str[end], str[start]             
            start += 1
            end -= 1