LeetCode/cs/construct-k-palindrome-strings.cs

public class Solution {
    public bool CanConstruct(string s, int k) {
        if (s.Length <= k) {
            // Can't construct more palindromes than characters, but when equal
            // can construct palindrome from each character.
            return s.Length == k;
        }

        var parities = new short[26];
        foreach (var c in s) {
            parities[c - 'a'] ^= 1;
        }

        return parities.Count(p => p != 0) <= k;
    }
}