Program to find possible number of palindromes we can make by trimming string in Python

PythonServer Side ProgrammingProgramming

Suppose we have a string s, we have to find the number of ways we can obtain a palindrome by trimming the left and right sides of s.

So, if the input is like s = "momo", then the output will be 6, as You can get ["mom", "omo", "o", "o", "m", "m", "o")

To solve this, we will follow these steps −

  • Define a function expand() . This will take i, j, s

  • c := 0

  • while i >= 0 and j < size of s and s[i] is same as s[j], do

    • i := i − 1, j := j + 1

    • c := c + 1

  • return c

  • From the main method, do the following

  • c := 0

  • for i in range 0 to size of s, do

    • c := c + expand(i, i, s)

    • c := c + expand(i, i + 1, s)

  • return c

Let us see the following implementation to get better understanding −

Example

 Live Demo

def expand(i, j, s):
   c = 0
   while i >= 0 and j < len(s) and s[i] == s[j]:
      i −= 1
      j += 1
      c += 1
   return c
class Solution:
   def solve(self, s):
      c = 0
      for i in range(len(s)):
         c += expand(i, i, s)
         c += expand(i, i + 1, s)
      return c
ob = Solution()
s = "momo"
print(ob.solve(s))

Input

"momo"

Output

6
raja
Published on 21-Oct-2020 15:47:27
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