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.

# @param {String[]} strs
# @return {String}
def longest_common_prefix(strs)
    return '' if strs.empty?

    (0...strs[0].size).each do |i| 
        char = strs[0][i] 
        (1...strs.size).each do |j| 
            return strs[0][0...i] if i >= strs[j].size || 
                strs[j][i] != char 
        end 
    end 
    strs[0]
end