# Rotate String in Python

PythonServer Side ProgrammingProgramming

Suppose we have two strings, A and B. We will rotate the string A and check whether it matches with B at any position of rotating, if so then return true, otherwise false. For example, if A = 'abcde', and B = 'bcdea' So answer will be true, as A can be converted to B after rotating it.

To solve this, we will follow these steps −

• When both A and B are empty, then return true, when both are of different length then return false
• A := concatenate A after A
• i := 0, and j := 0
• while i < length of A
• if length of A – i + 1 < length of B, then return false
• while i < length of A and j < length of B and A[i] = B[j]
• increase i and j by 1
• if j = length of B then returns true
• if j is not 0, then decrease i by 1
• j := 0
• increase i by 1

## Example

Let us see the following implementation to get better understanding −

Live Demo

class Solution(object):
def rotateString(self, A, B):
if not A and not B:
return True
if len(A) != len(B):
return False
A = A*2
i = 0
j=0
#print(A,B)
while i < len(A):
if len(A)-i+1<len(B):
return False
while i<len(A) and j < len(B) and A[i] == B[j]:
#print("Here!",i,j)
i+=1
j+=1
if j == len(B):
return True
if j:
i-=1
j=0
i+=1
ob1 = Solution()
print(ob1.rotateString("abcde", "cdeab"))

## Input

"abcde"
"cdeab"

## Output

True
Published on 16-Jan-2020 15:47:32