topic description
给定一个字符串，编写一个函数判定其是否为某个回文串的排列之一。
回文串是指正反两个方向都一样的单词或短语。排列是指字母的重新排列。
回文串不一定是字典当中的单词。
示例1：
输入："tactcoa"
输出：true（排列有"tacocat"、"atcocta"，等等）
来源：力扣（LeetCode）
链接：https://leetcode.cn/problems/palindrome-permutation-lcci
著作权归领扣网络所有。商业转载请联系官方授权，非商业转载请注明出处。explain the topic
Problem-solving idea: To judge whether a string is a palindrome sequence, one of the following two conditions needs to be satisfied:
- Each character in the string appears in pairs, that is, the number of occurrences of each character is even;
- The number of characters in the string with an even number of occurrences is even, and only one character has an odd number of occurrences.
Start solving problems (Rudy)
Check step by step
positive test case (ababa)
Negative test case (code)
absorb learning
