Write a function to find the longest common prefix string amongst an array of strings.
def longestCommonPrefix(strs: Array[String]):String = {
if (strs.length == 0) ""
else {
strs.reduceRight((s1,s2) => {
val l = s1.length min s2.length
var i = 0
while (i < l && s1(i) == s2(i)) {
i += 1
}
s1.take(i)
})
}
}
longestCommonPrefix(Array())
longestCommonPrefix(Array("a"))
longestCommonPrefix(Array("abc","abcdef","abpoiuyt"))