Write a function to find the longest common prefix string amongst an array of strings.

If there is no common prefix, return an empty string "".

  Example 1:

Input: strs = ["flower","flow","flight"] Output: "fl"

Example 2:

Input: strs = ["dog","racecar","car"] Output: "" Explanation: There is no common prefix among the input strings.

  Constraints:

1 <= strs.length <= 200
0 <= strs[i].length <= 200
strs[i] consists of only lowercase English letters.