leetcode: 14. Longest Common Prefix

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

class Solution():
    def longestCommonPrefix(self, x):
        if not x:
            return ""
        prefix = x[0]
        for i in range(1, len(x)):
            while x[i][:len(prefix)] != prefix:
                prefix = prefix[:-1]
        return prefix


if __name__ == "__main__":
    assert Solution().longestCommonPrefix(["China", "Chinese", "Chipotle"]) == 'Chi'
    assert Solution().longestCommonPrefix(["China", "", "Chipotle"]) == ''