You can use dynamic programming approach to solve this problem. dp[i, j] — minimum number of operations to convert substring s[i..j] into palindrome. Below is the transitions:

Obviously, dp[i, j] = 0 if i >= j

And in general dp[i, j] is minimum of:

• dp[i+1, j-1] if s[i] == s[j]
• dp[i+1][j-1] + 1 # replace character s[i] to s[j] OR s[j] to s[i]
• dp[i+1, j] + 1 # remove i-th character OR insert a new character right after j-th position
• dp[i, j-1] + 1 # remove j-th character OR insert a new character right before i-th position

The answer will be stored in dp[0, len(s)-1]

Hope that helps!

you can read more from here it's classic dp problem just find edit distance between the string and it's reverse