Reverse String in Python

PythonServer Side ProgrammingProgramming

Suppose we have an array of characters. We have to reverse the string without using any additional space. So if the string is like [‘H’, ‘E’, ‘L’, ‘L’, ‘O’], the output will be [‘O’, ‘L’, ‘L’, ‘E’, ‘H’]

To solve this, we will follow these steps −

  • Take two pointers to start = 0 and end = length of the string – 1
  • swap first and last characters
  • increase start by 1 and decrease-end by 1

Example

Let us see the following implementation to get a better understanding −

 Live Demo

class Solution(object):
   def reverseString(self, s):
      """
      :type s: List[str]
      :rtype: None Do not return anything, modify s in-place instead.
      """
      start = 0
      end = len(s)-1
      while start<end:
         s[start],s[end] = s[end],s[start]
         start+=1
         end-=1string_1 = ["H","E","L","L","O"]
ob1 = Solution()
ob1.reverseString(string_1)
print(string_1)

Input

String = ["H","E","L","L","O"]

Output

["O","L","L","E","H"]
raja
Published on 09-Jan-2020 09:23:53
Advertisements