LeetCode解题报告（312)-- 1332. Remove Palindromic Subsequences

Problem

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.

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: String is already palindrome

Example 2:

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

Example 3:

Input: s = "baabb"
Output: 2
Explanation: "baabb" -> "b" -> "". 
Remove palindromic subsequence "baab" then "b".

Example 4:

Input: s = ""
Output: 0

Constraints:

• 0 <= s.length <= 1000
• s only consists of letters ‘a’ and ‘b’

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Analysis

  题目给出一个字符串，允许的操作是每次移除一个回文子序列，问多少次操作能够把整个字符串清空。一开始想着要怎么找到回文子串，但是看了下题目发现这是道智力题。字符串中只包含两种字符，a和b，所以情况只有三种：

1. 整个字符串就是回文串，一次操作搞定；
2. 整个字符串不是回文串，首先把所有a都去掉，然后把所有b都去掉，两次操作搞定；
3. 字符串为空，0次操作。

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Solution

  无。

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Code

class Solution {
public:
    int removePalindromeSub(string s) {
        if (s.size() == 0) {
            return 0;
        }
        if (s == string(rbegin(s), rend(s))) {
            return 1;
        }
        return 2;
    }
};

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Summary

  看完分析之后发现这是道智力题，还是提醒自己注意审题哈哈哈哈。这道题目的分享到这里，感谢你的支持！