README_EN.md

266. Palindrome Permutation

中文文档

Description

Given a string s, return true if a permutation of the string could form a palindrome.

 

Example 1:

Input: s = "code"
Output: false

Example 2:

Input: s = "aab"
Output: true

Example 3:

Input: s = "carerac"
Output: true

 

Constraints:

• 1 <= s.length <= 5000
• s consists of only lowercase English letters.

Solutions

Python3

class Solution:
    def canPermutePalindrome(self, s: str) -> bool:
        mapper = {}
        for ch in s:
            mapper[ch] = mapper.get(ch, 0) + 1
        cnt = 0
        for _, v in mapper.items():
            if v % 2 != 0:
                cnt += 1
        return cnt <= 1

Java

class Solution {
    public boolean canPermutePalindrome(String s) {
        Map<Character, Integer> map = new HashMap<>();
        for (int i = 0, n = s.length(); i < n; ++i) {
            char ch = s.charAt(i);
            map.put(ch, map.getOrDefault(ch, 0) + 1);
        }
        int cnt = 0;
        for (Map.Entry<Character, Integer> entry : map.entrySet()) {
            if (entry.getValue() % 2 != 0) {
                ++cnt;
            }
        }
        return cnt <= 1;
    }
}

...