266. Palindrome Permutation

266. Palindrome Permutation

Given a string, determine if a permutation of the string could form a palindrome.

Example 1:

Input: "code"
Output: false

Example 2:

Input: "aab"
Output: true

Example 3:

Input: "carerac"
Output: true

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2 pass.
可以用set来实现single pass，加加减减

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