Leetcode #14: Finds the longest common prefix between the strings in an array.

LongestCommonPrefix.swift

func longestCommonPrefix(_ strs: [String]) -> String {
    var shortest = Int.max
    let charArrays = strs.map { (string) -> [Character] in
        let array = Array(string)
        shortest = min(shortest, array.count)
        return array
    }
    var outputChars = [Character]()
    for i in 0..<shortest {
        let ithChars = charArrays.map { $0[i] }
        let charSet = Set(ithChars)
        if charSet.count > 1 {
            break
        }
        else if let only = charSet.first {
            outputChars.append(only)
        }
        else {
            break
        }
    }
    return String(outputChars)
}