409. Longest Palindrome

    func longestPalindrome(_ s: String) -> Int {
        var map = [Character : Int]()

        for char in s {
            map[char, default: 0] += 1
        }
        var odd = false
        let res = map.values.reduce(0){
            if $1 % 2 == 1 { odd = true}
            return $0 + $1/2
        }
        return res*2 + (odd ? 1 : 0)
    }