[LeetCode]#1332. Remove Palindromic Subsequences

Environment: Python 3.8

Key technique: if

You are given a string s consisting only of letters 'a' and 'b'. In a single step you can remove one palindromic subsequence from s.

Return the minimum number of steps to make the given string empty.

A string is a subsequence of a given string if it is generated by deleting some characters of a given string without changing its order. Note that a subsequence does not necessarily need to be contiguous.

A string is called palindrome if is one that reads the same backward as well as forward.

Example 1:

Input: s = "ababa"
Output: 1
Explanation: s is already a palindrome, so its entirety can be removed in a single step.

Example 2:

Input: s = "abb"
Output: 2
Explanation: "abb" -> "bb" -> "". 
Remove palindromic subsequence "a" then "bb".

Analysis:

1. if s=’’, return 0
2. if s=reverse(s),return 1
3. if s is not 1 and 2 case, return 2.

Solution:

class Solution:
    def removePalindromeSub(self, s: str) -> int:
        if s=="": 
            return 0
        elif s == s[::-1]: 
            return 1
        else:
            return 2

Submissions:

Reference:

https://desolve.medium.com/%E5%BE%9Eleetcode%E5%AD%B8%E6%BC%94%E7%AE%97%E6%B3%95-85-string-3-7556d2f4cf7d